Unleash the Geek - Feedback & Strategies

[_CG_SaiksyApo]

The topic where you can tell how you liked the challenge, & how you solved it.

Leaderboard: https://www.codingame.com/leaderboards/challenge/unleash-the-geek-amadeus/global

[BlitzProg]

BlitzProg, 46th gold - 140 overall (2nd PHP)

I liked that contest! Unlike many others, the strategy that would focus on having the other lose the game (instead of winning fair and square) was a viable and powerful strategy. There was so many ways to fool your opponent, and not losing a bot to deceiving tactics ended up being so complicated.

I had to rewrite my AI many times :

• I entered the bronze league with a script that would simply pick the closest ore for each bot.
• I’ve beaten the bronze boss by dropping bombs while avoiding others (simply avoiding places where the opponent paused), and improve the farming.
• To beat the silver boss, I stopped dropping bomb, while improving my pseuso-detection of traps.
• I ranked up in the gold league by dropping bomb again but this time players had gotten really smart, so I blew the opponent myself.

My ending strategy was :

• evaluate the closest distances between bots and crystals and play the best finds. This was sub-optimal but did well enough in the gold league.
• avoid holes where the opponent pauses near - but only if the opponent paused at the left of the board (he requested a bomb. well, maybe)
• set bombs to the left of the game and use a simple AI for the opponent to detect where they would go, and hopefully predict in advance when there was an opportunity to kamikaze and take out more than one opponent bot with a single bot. Of course, this stopped being effective as others in the top of the league were also using that tactic - or simply dodging bombs, but it helped me gain many ranks. (250 ranks were gained with this hazardous strategy)

I had a lot of fun, thanks =)

[Illedan]

C# and should end around 90 after being promoted 10 min before the deadline
Fixed a few lines of code on my phone and it worked out

Had a great time streaming the contest, even though I saw a lot of bugs the next day when I reviewed my stream. ( Prize of coding 8 hours before the stream )

My bot is nothing special, just a bunch of behaviours:

• Place radar if I see less available ore than 2 x numRobots
• Carry a radar during normal mining to “trick” the enemy into thinking it’s a trap (also gains more vision, placement selected on Ore count + dist from other radars)
• Get traps if you can and Turn is > 5 and < 50 (random numbers, but helped in gold to have a few traps). Traps were placed during mining with no extra logic.
• Never move adjacent to an allied car if there is a bomb or an enemy can have a bomb nearby (greedy, moving 1 car at a time, ignoring the total best)
• Trigger any bombs if the loss is equal ( 1 for robots, 0.1 for carried items)

I also created a GA bot doing full moves, but I was struggling to get it to select good moves, so I threw it away on the last Sunday going back writing IFs…

On the game:

• Wish it wasn’t revealed. (having that week with some knowledge, but not all, kinda drains motivation)
• A little too much guesswork and cheese
• Much deeper game than I thought early on, which is very nice!
• Missing own Radar option and ore sprites being too equal
• Cool UI
• Fun to play

Thx for a great contest, I had a fun and exhausting time!

[BenjaminUrquhart]

Highest rank was 155 overall, finished 473rd for an unknown reason. Very triggering to lose 300+ places out of the blue, but there’s nothing I can do now.

This is by far the largest amount of code I’ve written for anything on CG. Just over 1.6k lines with 53k+ chars.

Despite the code size, my strategy was simple:

• If there are less than 10 accessible ore visible, put a radar down
• If a bot is free, start/continue constructing The Great WallTM
• All other bots either mine or bring ore back to base. If the bot is visiting a vein with 2+ ore, wait an extra turn in base to fake the placement of a bomb. The space is then reserved for late game mining.
• If a radar is available and the bot is mining a spot that’s not up against another radar, bring one along because it’s convenient.

After that, I check if I can kamikazee any enemy bots. If it’s worth it, I pull the trigger.

I also try to avoid sending more than one bot into an area where something is likely to explode. That was fun to program.

This was quite the game. I personally love games like this, it’s just sad that my placement got decimated like that.

EDIT: I had a different version in my IDE, that’s why it was so bad.

[eulerscheZahl]

I will finish around rank 20

This is one of the contests where I’m not sure if it’s worth writing a post mortem for my bot.
I use mostly heuristics to make my decisions, as I didn’t see the big picture on how to abstract the game and implement a decent search.

I generate a list of possible commands first. These are placing radars, harvesting and kamikaze attacks. Placing traps was part of it too, but I removed that part in legend. My bot is a pacifist.

I don’t have to say much about my radar placement, I probably lose some battles because of it.
The first radar is at (9,6) or (9,8) if there is no robot starting at y=6.
Then I try to cover large regions with my following radars, rewarding the placement on a known ore.

For harvesting I prefer cells close to the base obviously. I count the number of turns needed to reach the ore and bring it back to the headquarter. A cell with more than 1 ore gets translated into multiple actions.

Kamikaze actions will happen when I expect a good trade (like 2 vs 1) or an even trade (1 vs 1) while I’m in a lead. I also try that even trade when I’m not sure about the trap and I haven’t lost a robot yet, as that’s a relatively safe way to check if the trap is real or a fake.

I assign a score for each pair of robot and action. Then I reduce the amount of actions by removing those actions with low score for everyone. For the remaining actions I bruteforce all possible assignments. I give an additional score for the overall plan (e.g. a malus for having 2 robots next to each other, making them vulnerable for traps), which is why I didn’t use a more efficient Hungarian method.

When I plan to harvest on a cell with more than 1 ore, I wait a turn so the opponent fears a trap and hopefully won’t touch the cell, allowing me to come back later.

With my final destination cells in mind I can modify the movement path in order to penalty 2 robots being in the range of the same trap.

[raysplaceinspace]

I placed 67th in Legend League. I got to be 6th for a short while early in the contest before you all came in! Very keen to hear what the higher levels were doing!

This was my strategy:

• Like everyone else, watch enemies. When they stay still for 1 tick, assuming they are picking up or dropping off something. My bot would detect new holes or decreases in ore, then try to match them unambiguously to my own or enemy digs. If it couldn’t, all nearby holes were marked as potential traps.
• Pathfind around all potential traps. Only avoid traps that are reachable by the enemy. Most importantly, allow one bot through each potential connected explosions because if the enemy chose to kamikaze, it would be an even trade and no net loss or gain.
• Pretend to pickup traps - just wait in the HQ for 1 tick. Then “claim” an ore patch by digging it with what appears to be a trap. A smart enemy will not dig there. Now we own that patch and can go “claim” other patches. Continuously estimate the time required to dig up all our “claimed” patches to make sure we have enough time to actually mine them at the end.
• When choosing dig locations, consider the time to reach the ore patch and the time to return the ore. When choosing return locations, consider the time to the next ore patch as well.
• I also had a lot of code which would increase/decrease the likelihood of ore being in a particular cell given the results of random digs in neighbouring cells, but this was kind of made unnecessary with radars.

[Haashi]

Haashi, ended up 230th overall.

It was my first ranking contest (very first contest was thales-2018) and I didn’t have much time after Wednesday. Wednesday my bot ranked up 80th overall, and I did not change anything afterwards. I was pretty happy staying competitive without changing anything.

My strategy used really really simple heuristics :

• For every robot, assign every possible actions and do action with best score: dig, request trap, request radar, move to ore, wait at base

  • Dig : don’t ever dig if trapped by ennemy
  • request trap : if at base, request a trap at random (0.2)
  • request radar : if at base, and # of ores < aliveRobots
  • move to ore : move to closest ore (I didn’t use a custom pathfinding, so I was very vulnerable to the kamikaze strategy), if a robot is already assigned to this ore, move to the next closest
  • wait at base : random (0.05)

• All radar placements were hardcoded

• If one of my robot was near one of my trap, I checked the number of destroyed robots, if more enemy robots would be destroyed, I’d dig. (I once killed my last robot lol)

• To check enemy traps, If an enemy robot stays at base, I assume he has a trap until he waits again (Very very easy to trick)

Thanks for everyone playing and discussing the game in the chats, it helps a lot to read them to get some ideas.

[ndc]

Ruby -> Kotlin, #72 and still falling down at Legendary.

Planned to make beat-the-wood bot, so i started with a simple and dumb solution in Ruby. It become abomination of endless ifs, comments and stuff like if false and ... after a few days (and sneaking into gold league) , so i decided to rewrite it in some other language - Kotlin. New code was still a mess, but at least I fixed lots of bugs during the process.

My final bot was doing following:

1. Track enemy movements and try to predict when they retrieve items from base and dig them to create map of unsafe locations.
2. Decide do i need to place radar - just checking amount of visible ore above the threshold.
3. Give commands for my bots:

• If enemy close to a trap, trigger it. Did not work all the time, but sometimes destroyed other bots or enemy radars.
• Request item when at base.
• If carrying radar - place it in coordinates from predefined list. Later i added some deviation to avoid placing in enemy mines.
• If carrying ore - deliver it to base. This one was simple moving and to [0, robot.y] and most of my bots were destroyed on the way home
• Dig closest known and safe ore.
• Dig closest “?” cell if no ore.

Other things:
* First version of unsafe spots prediction was serious score boost and was dead simple - do not touch cells with holes.
* I tried different bomb placement patterns until i gave up and finished with single bomb solution.
* That single bomb was planted at the start of the match to counter guys that tried to steal my radars.
* Bomb wall tactic really worked for a few days until people started countering it.
* I somehow decided to use euclidean distance instead of manhattan. Did not realise i was wrong until i looked at referee code. Changing algorithm was surprisingly successful and gave me +100 places change.

Anyway that was really fun contest.
Thanks!

[RoboStac]

I finished 6th. At first I wasn’t sure about the contest, but ended up really enjoying it. My initial thoughts were bombs would be entirely pointless and it’d just be about fast farming, but I hadn’t considered the protecting of ore until later which made a massive difference. I never placed a single bomb as I was initially convinced they’d always be a waste of time (I now think this is wrong, but didn’t have time to add bomb support).

Before ever submitting a version I started making a sim using replays to validate - other than the randomness in long movements this worked well to prove there weren’t any issues. I used replays of the top bots at the time to develop / check bomb prediction. For both players I’d generate a list of possible bomb positions and which robots could be carrying bombs and then check that against the reality. This worked really well and made it easy to quickly advance up to the top of gold as I basically never died to a 1v2 and would never mine on an enemy trap. This worked by tracking changes to holes / ore and enemys waiting and matching them up. I also tracked radar timers and if the enemy only waited once per possible radar I assumed they weren’t bombing at all and cleared everything.

I never managed to make a good version that used the simulation - every version submitted was heuristic based. Every time I decided on a final move for a bot I’d work out where it would be at the end of a turn and then mask off any positions that could be exploded by an enemy (could chain from any square within 5 of any enemy) to avoid multiple losses.

In the end I had a few rules for moves:

• If any bots were at base and a radar was available take the radar (always before turn 150 or if there were spots that would reveal at least 5 new squares). The closest bot to the center would take the radar.
• If I had a radar on a bot and there were less than 5 ore available find the position that reveals the most squares (choosing closer positions if available and capping score for revealed squares to 30 to stop it going too far for a perfect radar). Until turn 125 this position couldn’t have an x coordinate less than 8 or be in the top 2 / bottom 2 rows.
• If there is a possible bomb on top of ore and there is an enemy bot in range of it then try to take that ore(1v1 trade + reveal fake traps).
• If there was ore that could be taken next to a bot, take the ore.
• If a bot was at base and hadn’t waited have a 25% chance to wait if there was at least 10 ore visible (didn’t want to waste time if down to the last few ore / when vision was limited at the start).
• If not carrying anything and there is an enemy bot that can be reached in one move that had waited at base and is next to multiple ore move on top of it (to help trigger the possible bomb exploding rule above )

Once all those rules had been checked the remaining bots would do a bfs to calculate time taken to collect ore and return it (or return ore and collect the next if already carrying). The one with the shortest time would be chosen and then the remaining bots would restart the search (as ore would be taken by the previous bot / moves would be masked due to explosion possibilities).

If I collected ore on a bot that had waited at base (or requested a radar) then I’d mark that square ‘protected’ and not collect from it until the last 75 turns.

I also tracked the maximum id seen when placing radars and worked out if it was possible to get to that id if the enemy had only asked for radars (as both bombs / radars would increment the id). If there was a good enough chance they hadn’t asked for bombs I’d ignore their bombs to try and steal their protected ore. This worked really well for a while, but there are a couple of people who only got a few bombs and didn’t radar spam which messed it up.

[miklla]

25th place. First of all I want to say that I enjoyed this contest very much. The game was surprisingly deep and contains many different aspects (e.g. scouting, enemy tracking, pathing, …) to master. A few cons were follow. It lacked clarification in statement what will happen if multiple robots try to dig 1 cell with ore. On 7th day my 2.2k lines of code reached code limit and I had to shorten my variable names, it was uncool.

First part of my algorithm detect enemy’s inventory and possible enemy’s trap places based on new holes, ore difference, score difference (I even lower ore in invisible cells if enemy robot visited only it among positive visits and then got +score). Changes in this part affect rating the most.

Then I calculate field map on 15 moves ahead and mark every cell to maximum number of neighbors(my robots) it can have in any point of time to set up Monte-Carlo for my robots. For example neighbors of enemy’s item holder may have 1 neighbor max, potential enemy’s traps have 1 neighbor max, in some situations like 1v1 with lower score I set 0 limit in some cells so my robot dodge kamikaze guy. Monte-Carlo was applied to tasks, not to moves. Example of task: move to (14, 10) in 4 moves. I wrote big pile of code to predict with high probability when all tasks can be realized under restrictions without need to simulate robot’s coordinates in mid-task. My calculations was so accurate that in half games predicted restricted minimal number of moves was 100% accurate whole game. Priorities were hidden in task generation, for example if I carry ore, then I check least moves for base cells, pick all of base cells corresponding to minimal number of moves and select 1 of them with higher probability the closer y coordinate to robot is. The best tasks are selected based on estimation function with decay over moves.

In the last part I calculate the best commands to realize found best tasks under restrictions, 95% of time default realizations works, in other times I Monte-Carlo commands to find the best to fit tasks. It is possible to kamikaze me 1v2 almost only via chaining, it is almost impossible without chaining.

In 1 sentence I detect enemies, Monte-Carlo on tasks level on 15 moves ahead, then realize found tasks in commands.

Regrets:

1. I don’t dodge chain explosions.
2. I don’t simulate opponent to figure out that I have no chances to reach some ore which he will reach before me and grab.
3. I don’t pick traps at all despite my bot is capable of suiciding in enemy traps with positive exchange like 1v2.

I say it again, thank you for great game!

[cegprakash]

Gold #263

My eval in my search looks like this…

score += 1000000 * oresCollectedByMe;
score += 10000 * myRadarsCnt;

for each enemy robot I score the following:
     if(enemyRobotDied) score += 9000000;

for each robot I score the following: 
     if(myRobotDied) score -=  10000000;
     else if(I just picked up an ore) score += oreHoldingScore
     else if(already holding an ore) score -= manhattan(0, orePickedUpLocation.y)
     else if (I just picked up a radar) score += 1000 - manhattanToRadarTarget;
     else if(already holding a radar) score -= manhattanToRadarTarget
     else {
           if(if I'm the closest robot to HQ and if none of my robots are holding a radar and there are no ores to collect){
	            score -= myRobot.x;
           }
           else if(turn < 2) score -= 10 * abs(myRobot.x - 8)
           else if(I have a safe closest ore location) score -= 5 * manhattan_distance;          
           else if(I'm digging a unexplored cell) score += 1;
           else score -= manhattan distance to closest unexplored cell. 
     }

Yet another addictive contest. I enjoyed the contest as I tried various strategies (capturing the center, various fakes, detecting fake etc.,). It’s just that search was over powered by decision tree bots.

Very sad that CG is stopping community contests. But thanks that CG promised to organize 2 contests an year. Please bring us at least 4 CG contests an year. We would love that.

[Taikha]

Ended 158th, not bad for my first contest, my bot do the following:

Enemy analysis:
Any enemy robot that pauses 1 turn in base will become a suspect.
Based on new hole or ore reduce with some check on enemy robot and my own action will mark dangerous tile.

Radar Point:
A precalculated weighted score graph for radar placement, all cell in range 4 add pts,
any new hole will within range will deduct the score. closest pt with HighScore * 0.9 will be my next radar point

Trap Point:
Building great wall at x=1 with available point closest to my robot

Fake Point(for robot faking):
Help building great wall at x=1 with available point closest to my robot

Dig Point:
closest dig tile available with checking on enemy robot position and their dangerous point

At game start robot with Y closest to middle will request radar, followed by trap.
All robot pauses at turn 1 and turn 2 to help fake the trap wall

Kamikaze move when predicted 2 robot coming and already there.

If my robot more than enemy, stop all kamikaze and stop fake and stop trap

To do:
need to analyze more on enemy robot pattern.

Overall, thanks for a great game ! enjoy it very much !

[k4ng0u]

k4ng0u, 18th overall (1st Typescript)

As I participated in the Amadeus internal challenge I had quite a head start understanding the gameplay and strategies. But you guys caught up quite quickly since by Saturday night the top players were already using everything that was used during the internal contest!
The key concepts for me were:

• suspicious robot: a robot that might have requested a trap (spent 2 turns at the base) and hasn’t dug since then.
• suspicious cell: a cell that has been last dug by a suspicious robot. This notion evolved a lot for me. It started as any hole on the map around which the enemy stopped. And by the end of the week it was a bunch of cells that were backtracked depending on robots, suspicious robots, my digs, current/previous map state.
• trap chains: chains of suspicious cells. In my algorithm I enriched it with the neighboring cells of suspicious robots as they could become suspicious by the time you move
• dangerous zones: the neighborhood of the trap chains that are reachable by the enemy (Manhattan distance of 4 or less)
  A lot of strategies were used during the contest and evolved in the time. Interestingly enough the evolution was similar during the internal and the public contest.

At first everyone would trap and kamikaze as often as possible. Then people would focus on avoiding traps and not spend time putting traps themselves.

Personally here was my strategy:

• Decision planning order: kamikaze, request radar, put order, request trap, put trap, go back to base, mine, go to base for next radar if no radar is being targetted, go around next radar spot, dig randomly
• Ore pathing: compute the 4 best ore cells for each of the mining bots. Bruteforce the best combination. Initially I used the nbMiningBots best ore cells but with 5 mining bots (5^5 combinations) my code was occasionnaly timing out)
• On a given turn, avoid to have more than one robot in the same dangerous zone (avoid multiple kills) => this is done after all actions have been planned and in a way so that robots are as close as possible to their initial targets.
• Whenever I am next to a suspicious cell with ore that has more enemies than allies around it, dig in it. (=> worst case it’s a trap, you lose one unit and enemy loses one unit. best case scenario you destroy a radar and get 1 ore. In between you go away with 1 ore. And in all cases the cell is no longer suspicious)
• My radar positions were fixed (+/-2cells depending on whether cells are suspicious or not) and not replaced if destroyed as I rely on my map history and good suspicious cell determination.

With this, I was in legend as a pacifist bot that would only explode a few enemy traps in my quest for Amadeusium.

In legend a new strategy appeared: making every bots suspicious by having them wait 1 turn at the base. This would slow down the enemy who will have to avoid all the suspicious cells and need to find his ore further. And then at the end of the game, it’s harvest time for incredible come back effects or just winning harder at the end of the game.
I went for this and it pushed me in the top 10.
However a counter strategy came out: some people were systematically mining near my bots to determine whether a suspicious cell is really suspicious. And probably if this was working well X times, he would just mine without caring of whether the cells are suspicious or not.
To face this, on Sunday evening I had to add a few traps in my algorithm just for the disuasion effect.

In the end I finished at the 18th place which is my best result so far. Paradoxically I am a little disappointed since I was in the top 10 most of the week. But well I guess not everybody kept their best bot in the arena
The fact that multiple strategies were countering one another was interesting and made it challenging to perform well against every opponent type.
On the downside I would point the viewer that could have included the possibility to show the radar zones of both players.

Thanks codingame and Amadeus for this challenge. It was very entertaining!

[Magus]

I’m 132th. I didn’t have much time for this contest so i tried some research algorithms :

• A bruteforce of every possible moves for each robots. I bruteforce all moves for my first robot, i keep the best, then i bruteforce all moves for the second robot, i keep the best. This goes on until the last. To evaluate a move, i use an evaluation function but i also bruteforce all enemy possibles traps (DIG a trap or explode a traps).
• ISMCTS : It’s like a MCTS but you randomize the unknown. It’s was terrible.
• Monte Carlo depth 1 : Not really good.

I suppose i could do better with a simple heuristic code, but it was not fun.

On the contest itself :

• The concept is good
• I think the trap mechanics could have been better. Not really sure how.
• Incomplete information. Can be good. But because of this, you have the “shi fu mi” effect.

In fact, i think the contest could have been better with a different trap mechanic and with a 1v1v1v1 mode (4 players).

[Hikari42]

I finished 30th in legend, it was the first time I reached legend so that was great for me.
My strategy was to estimate the 5 best “goals” for each robot (for example dig in a particular cell and get the ore back or take a radar and place it), then I optimized the combination of moves (by brute fore, with 5**5 = 3125 possibilities) to avoid having two robots that can be killed by a kamikase and to avoid two robots having the same goal. I tried to implement a “yolo” strategy where I assume that there is no trap placed if I’m loosing to much to try to get back in the game but it never really worked.
In addition, I also tried to obtain as much information as possible from enemies moves.

Overall, I found the challenge great, being simple and deep. I found particularly interesting to discover environment through opponent moves. However, there was a meta effect a bit too strong : the optimists beat the prudents who beats the aggressive who beat the optimists. As a result, after a certain points, it was difficult to know if a change would improve your bot.

I also think that the traps and radar mechanisms were unbalanced. If you lose one more robot than your opponent in the three first quarter of the game, you basically just lost so you cannot really adapt to the strategy of the opponent. Similarly, I believe the radar were too powerful and just forced everybody to use them all the time. Maybe having 10 robots each instead of 5 and radars with 1 less range would have authorize more different strategies.

Also it would be great to have a special display for battles where your bot timed out.

[teccles]

I came in second, which is becoming a habit. Thank you very much to the creators, sponsors and organisers of this competition. As ever on CG, it was very smoothly run. Congratulations to @karliso on a great win. Going into the final hour, I knew I was winning 70-80% against all the top published bots; but karliso’s last minute entry blew me away.

The trap meta

I’m going to spend most of this post talking about the meta around traps, the most interesting/difficult/important part of the game, and how my bot fitted with that. To do that, I’m going to go through strategies around traps, working from the simplest strategy through the various counters and counter-counters.

1. Mine ore, ignore traps

There’s not much to be said here. The first iteration of my bot, and probably most bots, placed radar, mined ore, and never thought about traps. This quickly becomes untenable.

2. Place random traps

If you place random traps, opponents who ignore them will blow up their robots. This is a devastating thing to happen. You lose 20% of your mining power for the whole game - this is usually decisive.

I went through a phase of doing this. I found it effective for reaching the top ten (very early on), but you can avoid digging up traps by detecting them. There are at least two ways to achieve this:

• Avoid any square your opponent’s robot has paused next to, which has a hole.
• More sophisticated, only avoid squares which robots have stopped on after pausing on the HQ.
  • This can be countered by robots holding traps visiting HQ briefly. However, this is easily detected - your opponents score doesn’t increase, so you know something funny is going on.

I did these methods of trap detection. This allowed me to perfectly avoid traps, when I wanted to.

3. Suicide on traps

Here, you dig up a place you know (or suspect) is a trap, to take out two of your opponents robots for one of yours. When I did traps, I did this.

This is avoided simply by never having two of your robots next to an enemy trap, or chain of traps. However, by the end chains were so rare that I only considered single traps, to improve pathfinding.

4. Stashes

This is where things get interesting. Around Thursday of last week, a new meta emerged. @The_Duck was the best at this for a long time, though I don’t know where it originated. The idea was:

• Pause your robot on spawn, but don’t pick up a trap.
• Dig a square with more than 1 ore. The opponent will think it might be a trap.
• Leave (stash) the rest of the ore for later. When ore goes short, go back for the easy pickings.

In the high level meta, most or all bots were using this by the end. I was, whenever I expected to dig a 2 ore square early in the game. I started picking up stashes at a hardcoded turn, or when the nearest ore to HQ got far enough away.

5. Stash detection/guesswork

Stashing is so effective that countering it became (I believe) the key to the high-level meta at the end of the competition. I tried multiple methods to detect enemy stashes. Having done this, you can dig them up safely.

• Entity IDs. Traps and radar get IDs which are sequential, shared between opponents, and set when the item is buried. This means that if you place IDs n and n+1, nothing buried between those placements is a trap. This is the only certain method in this section; the rest is guesswork.
• Obvious radar. If there are no possible radar anywhere near the item buried, it’s a radar. If multiple holes dug after it is buried would be invisible without this item, it’s a radar.
• Two enemy robots next to a square, when we have a robot nearby. This uses point 3 - the enemy wouldn’t take that risk. To avoid this being used against me, I avoided having two robots next to my own stashes at once.
• Late traps. Very few good bots placed traps after around the halfway point in a match, so it was often worth the risk. This risk almost certainly ended up costing me the win - karliso did this much more, and many of my losses to them came from late traps.

I tracked the expected result of the game, and took more of these risks when behind. Also, if there is an enemy robot next to a stash/trap, I dig it. If it’s a trap, it’s a one for one swap.

Other aspects

To pathfind, I guessed which ore each miner would go for. Then they got to select routes, starting with the one closest to their target. These routes were planned so that we’d never end up with two robots next to a trap/stash on this or a future turn. Within that restriction, I prioritised being close to enemy stashes but not my own.

My first few radar are hardcoded, except that I skip the risky second and third radar if the first doesn’t turn up enough ore (so that I don’t run out). After that, I mostly place them opportunistically as I mine, which is a very effective technique.

There’s lots of other code in my bot, but none of it stands out as particularly interesting or important.

Final evaluation

This section is a tad salty, so let me preface this by saying that I was beaten by a great bot, and by again expressing my thanks to everyone who had a part in the making of this great contest.

In the final evaluation, karliso and I had very comparable results against lower bots; perhaps mine are slightly stronger; the bulk of the gap between us comes from our head-to-head record. This record was 54-37. That is within the range of normal outcomes from a fair coin toss. For future contests, particularly with significant prizes, I think that there should be more games run in the evaluation; I think there is a 10% probability I would have won the contest in this case (and if the evaluation had been closer, this chance could be much higher!).

Again, karliso is a worthy winner, I have no bitter taste from this contest, and I hope to play many more CG contests in the future.

EDIT: @Neumann pointed out that not all the games in the final evaluation are on CGStats, because there is some maximum number tracked and they get forgotten over time. So the actual sample size is larger than I quoted here, and this the evaluation is more rigorous than I thought.

[DaFish]

24th in legend, very surprising because my bot lacks very basic stuff due to lack of time, for example it can be easily 1v2 kamikazed. Luckily, the better the opponents, the less this happened!

The only “smart” thing my bot did that has not been mentioned already is that if an opponent starts harvesting a “stash” (see teccles post), and there is still ore left on the stash, then my bot realizes that there is no bomb there and will prioritize emptying that enemy stash. Don’t know if it helped much though…

It was refreshing with a “heuristics only” contest, although not really my cup of tea, it makes programming much more recreational (“ah, let’s add another if here and see what happens”)… the rules were very simple, and still there was a lot of depth, kudos to the organizers!

[vrampal]

Hello,

I was part of the testers of the game and out of the competition but I can give you a few explanation on my strategy.

The main idea was to create a very fast collector that does not spend time setting traps.

My radar position was hardcoded, nothing fancy. I decide to put a radar or to continue collecting based on the amount of visible “disputed” ore. I choose my radar carrier to minimize the total travel distance.

I don’t try to avoid “dangerous cells“ for radar because I am generally faster than my opponent. If the opponent destroy one of my radar, I will restore information from previous turn. It does not affect me and I don’t waste time setting it back.

A large part of my code is analyzing the difference between actual map and expected map and correlating with the movement of opponent robots.

• Cells with unexpected hole or unexpected missing ore are flagged as “touched cells”.
• If an opponent robot stays in column 0 I flag the robots as “carry item”.
• For each “touched cell”, I check how many opponents robots stays near it. If it’s only 1 I associate this robot and the cell. If the robots “carry item” I will remove this flag and flag the cell as “dangerous”.

This allows me to resolve some actions but not all. In case of ambiguity, I flag all cells with a hole near a robot carrying item as “dangerous” without removing the “carry item” flag on the robot.

When 1 or more opponent robots reach the base, I compare if the score increment with the number of returning robots. If it matches, I know all robots was returning ore, they are now empty and I remove flag “carry item” on them.

This game me a pretty good vision of my opponent tactics and I was able to do kamikaze attacks on “dangerous cells”. Very powerful.

I also estimate if my opponent is using trap before searching for kamikaze opportunity. I could how many item was requested during the last 5 turns. If it never goes above 1, you should be safe.

My code create some stats of the map. How many “dangerous cell”, how many “dangerous ore”, how many “protected ore” (below one of my radars), how many “disputed ore”, how many “double ore” and how many “triple ore”.

Depending of these stats, I sometime choose to wait at the base before digging a double ore or a triple ore. The cell is them marked as “protected”; I don’t expect the opponent to touch it and the remaining ore is collected only at the end of the game.

I didn’t created any to code to protect from kamikaze, didn’t have any path-finding to adjust my path.

The code is 860 lines long, I was very surprised to reach legend league.
At the end, even if I never take a trap, it rely a lot on the fact I could have set a trap.

[TheBronx]

Thank you guys for sharing the strategies. I have used many myself but there is one thing I didn’t think of that many of you have mentioned:
Waiting a turn in base to protect your stashes with fake traps.

Ended up in Gold #252 with a “simple” javascript bot that just had a list of moves ordered by priority:

• request a radar
• go base to deposit ore
• move and place a radar
• dig big stacks once, before the enemy (this would have been much better combined with the fake bomb strategy)
• move and extract closest ore
• blind dig

Each move of course had some preconditions but nothing too sophisticated.

This worked well until Gold League. Moving 5 bots without a BFS algorithm proved quite difficult. Things started to get really complicated when I had to prevent multiple bots from doing the same move for example, or going too close to each other. At this point adding/changing preconditions and deciding objectives was not the way to go. The final version was around 800 lines of code, mostly clean except from a couple 30 loc methods haha.

Anyways it was fun and I wasn’t expecting much, just wanted to jump in quickly and spend some time being creative.

The starter AIs were super helpful BTW. Parsing inputs is such a pain in the ass!

What I struggled the most with was discovering if a new version of the bot was better or not. Waiting till all battles are finished is boring so I keep coding. By the time the battles end I have added or removed something, changed a parameter… and it is hard to clearly see what change is responsible for what. Did I drop because of X? Or was it Y? Maybe it is the combination of both. But wait, now that I have changed this maybe the new version works better.
In other words, quick feedback. It is like executing the tests while coding and finding out that something is broken 10 minutes later but you cannot see what test is failing and your code base has changed meanwhile

I haven’t tried executing matches locally. Maybe I should try that and compete with previous versions of my code to get an idea of what works and what doesn’t without having to wait that much.

PS: I have been writing some posts about my experience during the contest if anyone is interested https://salvatorelab.com/tag/unleash-the-geek/