Starcraft AI blog

I think AITP is the only AIIDE 2019 bot whose game play deserves its own post. Most others can be watched at SSCAIT and BASIL, and BunkerBoxeR is severely buggy. AITP finished second to last, but it is complex and interesting. In this post, the game links are links to replays; you’ll have to drop them into the OpenBW player yourself.

AITP is derived from Steamhammer and shares some of the same habits. For example, it places supply depots and other buildings of the same size preferentially at the edge of the map, like Steamhammer terran. As explained in what AITP learned, the bot has an interesting abstract strategy system that is different from any other Steamhammer derivative.

AITP does not have strategy work only. It knows how to make a wall at the ramp, how to lift the barracks to open the wall, and how to land the barracks nearby to leave the wall open. It also knows how to lift the barracks back and restore the wall in case of danger. It researches spider mines and lays mines in neat diagonal lines in places like the approach to its natural. Later in the game, when it has a dangerous tank ball, it moves out and sieges to cover movement routes, like SAIDA but with less understanding of where the important places are, and builds turrets there. It has an excessive desire to build bunkers in the middle of the map, which it then doesn’t use properly.

It has also lost important skills that it inherited. It seems to have lost the emergency reaction of taking SCVs off gas when mineral mining is more important because of a large gas excess. Marines may stand away from a bunker that they should jump into, a new and critical misplay. AITP often moves its army away from the action toward a distant empty base, as in this game versus XiaoYi on Fortress (possibly a bug in deciding on the squad target).

Overall, I judge AITP as promising but not mature. I imagine that the tournament came up too early in its development. Some of its skills are impressive, others look incomplete or broken. It needs work to fix bugs (223 crashes during the tournament), polish skills, and add strategy modules to cover more cases. If it gets that work, I think it could become very strong.

Here are my observations of how AITP played when following each of its 5 declared openings. I correlated its learning files with the detailed tournament results to find games with each strategy. Later I’ll read the code and decipher the strategy modules more fully. All strategies involve initial buildings placed at the base entrance. On the map Aztec, where the main base is on low ground below a ramp, it smartly builds at the entrance to the natural instead of the entrance to the main. Few bots know to do that; even Locutus got in some trouble by not doing that.

Every one of these strategies is defensive, as you might expect with buildings at the entrance. I think AITP has good vulture micro and would benefit from having the option of more aggressive vulture play. Also none of the openings is honed to a fine edge; they are all a little rough.

A1-B1-B2-C2 Make a very fast barracks at 5 supply, placed at the base entrance, then finish the wall with a bunker and supply depot. This is the build labeled AntiRush. Later add more barracks and get medics (though no marine upgrades) and move out. I initially guessed that AITP played factory unit mixes every game, but this is a barracks unit mix. This plan scored wins only against random UAlbertaBot, which of course favors rushes. Here is a win on Heartbreak Ridge versus protoss zealots.

A1-B3-C2 Make a very fast barracks at 5 supply, placed at the base entrance, then finish the wall with a bunker and supply depot (this part must be A1). Follow up with factory and ebay and turret up the base. Get vultures with speed first, then expand. Eventually switch into a tank-goliath unit mix (I’m guessing this is C2, which if true means that I didn’t see a game with the anti-rush A1-B1-B2-C2 strategy which got as far as stage C). This was AITP’s most successful strategy by far, in fact I would call it the only successful strategy. It was a top choice against ZZZKBot, Microwave, McRave, UAlbertaBot, and BunkerBoxeR. Here is one of AITP’s 7 wins against Microwave on Python where Microwave played a 9 pool and followed up unambitiously.

A3-B5-C1 Narrow the base entrance with supply depot then barracks, and start a factory before the first marine. Get vultures with mines first and remain defensive. Start a command center in the base, and keep making vultures. When the command center is done, float it into the natural, keep defending with the vultures, and finally add tanks before moving out. This strategy scored zero against every opponent except BunkerBoxeR, which played broken builds. In the first game versus Iron on Benzene, AITP put up a creditable fight.

A3-B7-C1 Narrow the base entrance with supply depot then barracks, and start a factory before the first marine. Get vultures with mines first and remain defensive (up to here must be A3). Then get tanks and start a command center in the base. Not a suitable opening against aggressive play. When there are 2 tanks (no siege mode), lift the finished command center toward the natural. This plan did not show good success against any opponent, but worked better than A3-B5-C1 above. Here is a game versus McRave on Destination.

A4-B2-C1 Wall the base entrance with barracks, depot, bunker, in that order. Make marines and vultures and a fast ebay for turrets. When there are 5 marines, push out, bunker the natural, and expand. The strategy does not impress me; it is not greedy enough to gain an advantage against a cautious opponent (DaQin), and as implemented not safe enough to survive an aggressive opponent (Microwave). Watch how effortlessly PurpleWave wins with 2 dragoons and straightforward play when the 5 marines move out; AITP is missing the defensive skills to make it work.