Starcraft AI blog

AITP scored zero against over half of the participants, so its learning results are not deeply interesting. Also, its strategies are labeled with opaque sequences of letters and numbers. But it was easy to generate the tables, and they offer a little insight into AITP’s interesting design, so here they are.

Unlike other Steamhammer forks, AITP does not spell out concrete opening builds in the configuration file, at least not beyond 4 x SCV—start by making workers. The strategy names themselves are code sequences that tell what to do throughout the game. The letters A, B, C are stages of the game, and the combinations A1, A2 etc. are “modules” that may be active during the matching stage. Each module has its own update method to decide what to build, and the StrategyManager sometimes checks the current module for other decisions. There is module switching code in case of surprises (StrategyManager::shouldSwitchModule()); it also sets flags and updates other information.

I like it, it’s a flexible way to specify a plan for the whole game, and allows for changing plans on the fly. It’s an abstract strategy system, similar in principle to what I plan for Steamhammer. My implementation will look entirely different, though.

AITP has only 5 strategies configured. I gather that it can switch to other sequences on the fly if circumstances warrant. 5 is not many, though; I think they have only completed the basics. Here is the Steamhammer opening group it assigns to each strategy. It does not use the opening group strings, but they may have some heuristic value:

• A1-B3-C2 AntiRush
• A1-B1-B2-C2 Rush
• A3-B5-C1 NoneBunker
• A3-B7-C1 NoneBunker
• A4-B2-C1 8BB (does that mean BBS?)

AITP lost every game, but did not explore its possible strategies equally. It seems to have priorities. Maybe later I will look into how that works. AutoGasSteal is set true in the configuration file, but AITP did not record itself as stealing gas against any opponent. Presumably it is turned off in the code.

Steamhammer is the highest-ranked opponent that AITP scored wins against. It looks like a few scattered games, though.

It looks like ZZZKBot played its 4 pool in over half the games, and perhaps its guardian rush in the remainder. A1-B3-C2 is the strategy labeled AntiRush. AITP recorded more wins for itself than it actually scored, despite recording fewer games than it played. I suspect that AITP has changed the meaning of the numbers.

Again, AITP recorded fewer games and more wins than happened. Is it a bug, or is it intentionally over-recording wins for certain strategies to focus its search? Or what? AITP is interesting, it deserves a closer look into the code.

DaQin is derived from Locutus and also keeps 200 game records. But DaQin did not have pre-learned data. No games were left uncompleted; there are 100 against each opponent.

DaQin plays fewer builds than the other bots I’ve looked at so far.

DaQin had an enemy-specific strategy configured for Locutus, so it didn’t try anything else. Locutus is the only opponent that DaQin tried to prepare for, as far as I can see.

DaQin incorrectly recognized dark templar rush as Locutus’s strategy in most games, then correctly recorded that no cloaked units were seen during the game. See yesterday for Locutus’s play against DaQin, which did not include any DT build. I assume that the dark templar recognition is deliberately over-cautious, because DTs are dangerous. Locutus does have a fake dark templar build, where it adds a citadel of Adun to fool opponents into expecting dark templar (it works against most UAlbertaBot-derived bots).

Against PurpleWave, in contrast, DaQin less often foresaw dark templar, but apparently often faced them. (Arbiters can’t get out that fast.)

How did ZZZKBot upset DaQin? These numbers suggest zergling bust (it could be hydras, but DaQin does have a hydra bust recognizer which did not fire): Mostly “heavy rush,” few mutalisks, no lurkers. Steamhammer also settled on zergling bust as the best bet, but was much less successful. Microwave tried its zergling bust build versus DaQin without success. Maybe ZZZKBot’s extreme aggression is the key.

12NexusCarriers seems to be the default build versus terran. Apparently terrans, even Iron, were not able to punish the fast expand. Well, they’re not supposed to be able to without risk, that’s the point of cutting probes for nexus on 12, but it does require good play from protoss to ensure.

XiaoYi usually got air tech pretty fast, that’s unusual and interesting. I’m guessing it scouted the carriers coming and prepared wraiths.

McRave upset DaQin. Dark templar in 3 out of 4 games, and they came out pretty early. PurpleWave showed a similar pattern, but it wasn’t as salient because it wasn’t an upset. The dark templar rush recognizer did not seem to be fully effective, possibly because it was overridden by the fast rush recognizer. DaQin’s best counter was DT-back-atcha.

DaQin had some trouble adapting to random UAlbertaBot. This is a point where preparation for the opponent would have been valuable: Make a build that UAlbertaBot can’t beat and ensure that it is played. It can be a general-purpose build; PurpleWave included a cannon turtle build that is safe against all sorts of rushes.

Beating BunkerBoxeR with a build of fast expansion into carriers is... not the intuitive choice. But I guess it worked.

New bot Feint appears to be a feint. It looks like a recompiled Steamhammer 2.3.5 playing terran; the DLL files are the same size in bytes, and even the bot and author names in the configuration file have not been touched. It this a test and it will be updated, or is it a throwaway?

Locutus’s game records are in almost the same format as Steamhammer’s and can be summarized by the same script. I expect it will also work for DaQin and AITP.

Where Steamhammer was set to keep 100 game records per opponent, Locutus was set to keep 200. Since there were 100 rounds in the tournament, game counts over 100 mean that pre-learned data is included in the table alongside the tournament data. If Locutus was not trained on a near-final version of the opponent, then the two could be significantly different.

After seeing a few Locutus-PurpleWave games I got the impression that PurpleWave reacted adequately to Locutus’s trick strategy of cannoning the ramp and then dropping zealots. So I was surprised that Locutus considered it the best choice. But the overall win rate is high compared to the tournament results, so I suspect it is influenced by pre-learned data from games against a weaker version of PurpleWave.

The numbers in the “recognized” columns of the plan table show how widely Steamhammer cast its net for a solution to Locutus.

Locutus never tried to steal the gas of a zerg. Objectively, that makes sense. In the context of bot play, I’m not so sure; many bots of all races mess up their builds in the face of a gas steal.

Locutus declared an enemy-specific strategy against Iron. I’m not sure why it also had pre-learned data.

Proxy DT rush. That tends to confirm my picture of XiaoYi as vulnerable to tricks.

Locutus configured an enemy-specific strategy against UAlbertaBot. Openings other than CannonFirst4GateGoon are from pre-learned data, which was ignored in making the opening decision.

Today is Steamhammer. With a mid-rank finish and the widest range of builds, plus informative game records, Steamhammer may give us the best insight into how other bots played.

The tournament was 100 rounds, and Steamhammer was configured to remember the previous 100 game records, because in play there is no reason to remember more (earlier records are increasingly discounted). Steamhammer also had pre-learned game records for many opponents, so when the game record count reached 100, new records added caused old pre-learned records to drop away. Not all 100 tournament games happened for each opponent, but the pre-learned games filled in the small gaps so that Steamhammer ended up with exactly 100 game records per opponent in every case.

The “opening” table counts Steamhammer’s opening choices. The “plan” table shows the plan that Steamhammer first predicted that the opponent would play, then recognized that the opponent was playing. Both prediction and recognition can be wrong. The timing table is new this year, an attempt to get a little more information out of Steamhammer’s rich game records. For some events, it gives the count of games in which the event occurred, and the median time, earliest time, and latest time it occurred in those games when it did. The times are given under the assumption that 1 second of game time is exactly 24 frames, a simplification.

• gas steal attempt - When Steamhammer sent out the drone to steal gas (if it did).
• gas steal success - Whether the gas steal attempt succeeded in taking the opponent’s gas. Steamhammer doesn’t record the time it happens, so this is only a success count.
• enemy scout - When the enemy scout first reached Streamhammer’s base.
• enemy combat units - When the first enemy combat unit was seen.
• enemy air units - When the enemy is first known to have tech for flying units (except overlords).
• enemy cloaked units - When the enemy is first known to have tech for cloaked units.

It looks like Locutus opened forge-expand every game. It worked. Steamhammer desperately tried everything, including ZvZ builds and island builds, and finally squeezed 3 wins with a risky extreme macro opening, 4 hatcheries before spawning pool, which was able to win one game in five. I should add 5 and 6 hatch before pool and see if they help.

Locutus rarely made corsairs or dark templar. I wonder what its criteria are? Maybe it won before it got that far. The scout was usually quite early, and the first combat unit was seen late, as expected for a cannon-first opener.

I played over the 3 wins. They were in rounds 65, 70, and 73; after that, I expect that Locutus found a way to win. In 2 games, Steamhammer pulled ahead in early economy with its greedy opening, then struggled to defend and fell into a losing position. But Locutus got most of its units stuck in its base, and Steamhammer was able to turn it around and win after a hard fight with critical defiler support. In the third win, Locutus chose a zealot-archon unit mix that Steamhammer knows how to cope with, and zerg powered through.

PurpleWave in contrast went with mostly 2 gate openings against Steamhammer; that’s what “heavy rush” means for protoss. Steamhammer countered with early sunkens plus hydras or, less successfully, mutalisks (this version had a bug that weakened mutalisk play). There are also 3 wins with a ZvZ fast mutalisk opening. 2 gates should beat that, so protoss either played poorly or chose a different build in those games.

BananaBrain contrasts with both previous opponents in that it played a variety of builds. Steamhammer was unable to predict what was coming. It looks strange that the best reaction was an opening designed to counter terran factory-first builds that include a vulture runby, but in fact it is a mildly specialized 2 hatch mutalisk variant and not so surprising. BananaBrain made corsairs and dark templar in most games.

DaQin played forge-expand and has similar timings to Locutus, for the same reasons. The fast scout is to allow adjustment of the cannon count and timing, and the late combat units are due to getting a gateway later. Steamhammer couldn’t find any better reaction than to try to bust with zerglings, either early or late, and it was not particularly successful.

ZZZKBot mostly played a turtle-into-mutalisks strategy against Steamhammer, and was somewhat successful. You can read the idea straight out of the tables above. The 2:25 earliest timing but 4:06 median timing for combat units says that ZZZKBot sometimes rushed zerglings, but usually not.

Microwave played a 9 pool speed build into expansion and then spire, which you cannot read out of the plan table because Steamhammer didn’t recognize it accurately. But in the timing table you can see that combat units (zerglings) were early and air units (mutalisks) were not late.

Steamhammer was not able to steal Microwave’s gas. It probably should have stopped trying.

Look at that huge range of scout timings! 0:34 means that the scout SCV was sent immediately at the start of the game and went directly to the zerg base. 15:09 probably means that no enemy unit got into the base until the end of the game when Steamhammer lost (Steamhammer is on BWAPI 4.1.2 and cannot detect scans). Steamhammer prevented the scout entirely in 13 out of the 100 games by its own count; 15:09 is probably the same. Steamhammer was not able to steal Iron’s gas, and did eventually give up trying.

Steamhammer liked 7 pool against XiaoYi, just as Microwave did, but also liked its dawn hydra rush.

Thanks to pre-learning, I expected Steamhammer to play its overpool turtle build every game. I’m not sure why it didn’t. I also don’t know how it hit on the 5 scout build, which means send out a drone at 5 supply to scout very early, then leave all decisions to the strategy boss. It’s a logical try against a random opponent, especially one that has a single strategy for each race, and it was fairly successful. But it did not appear in the pre-learned data.

AITP scored zip against both mass zerglings (9HatchExpo9Pool9Gas) and against fast mutalisks (AntiFact_13Pool). And it successfully scouted Steamhammer’s base only 25% of the time. If you don’t scout reliably, it will be hard to withstand rushes.

Steamhammer was not able to judge whether BunkerBoxeR was playing a proxy (with its proxy bunker) or a worker rush (since it sent SCVs in support). But it didn’t matter. The reactions are nearly the same. Since BunkerBoxeR never wants gas, stealing its gas was a waste.

Steamhammer knows 142 different openings. In the whole tournament, it was only able to try 111 of them! It tried the most openings versus protoss, since it was looking everywhere for an escape from the overwhelming top protoss bots. Most openings were tried only a few times and lost every game, which means that Steamhammer would have performed better without them. That’s expected and even intentional; my plan is to add smarts until it is able to make good guesses about what to try. The work is underway.