Starcraft AI blog

Today I list the big changes in Steamhammer 2.0 without going into detail. There are tons of smaller changes. Details will follow.

The most effective changes:

• squad units are clustered, and each cluster makes attack/retreat decisions independently
• mutalisk and especially hydralisk micro is crisper
• a base under attack does not receive transferred workers, improving resilience
• greatly reduce cases where the bot gets a spire/lurker aspect and then delays getting mutas/lurkers

The squad unit clustering allows Steamhammer to play a big army macro game without the constant tactical blunders that it used to make (it makes smaller and mostly different blunders). Many bots use a similar system, with good reason. The tactics rework is substantial, and deserves the 2.0 version number by itself. In combination with the other improvements, Steamhammer is incomparably stronger at ZvP, which may now be its best matchup. I reported on DaQin, and Steamhammer (like Proxy) can open with 12 hatchery and still cope with Wuli’s rush (Proxy’s author called it easy, but it requires a combination of several skills that are not so easy).

I put in a ton of work, but the decisions that unit clusters make are still not as polished as they need to be. An interaction with the combat simulator causes dangerous mistakes in retreating from superior forces. It can happen in all matchups, but it is most obvious in zergling fights in ZvZ. What used to be Steamhammer’s most successful style of play in its best matchup is now its least successful in what may be its weakest matchup. It’s pretty funny, or at least it will be after I figure out how to fix it.

All these items deserve their places on the list. I fixed the case where Steamhammer’s spire used to finish and it would make a bunch of drones instead of mutalisks, and that may sound like the usual modest improvement to the strategy boss. In fact it is a critical fix that makes midgame tech switches more rapid and decisive. It wins games.

Other important changes:

• mineral locking
• base defense was reworked extensively
• new openings added to exploit possibilities and old openings tweaked to fix flaws that had crept in
• opponent model exploration and strategy randomization improved
• defiler support with all spells: consume, dark swarm, plague

Many aspects of play have moved forward. As always, there are new bugs like the retreating problem I mentioned above. And as I blathered about yesterday, old weaknesses remain. The overall result is as I’ve reported before, hugely stronger play against some opponents and weaker play against others. Well, that’s in my testing, which is never enough. We’ll see how it goes in the wide world! Since we’re in a time of protoss domination, I’m thinking that strength against protoss is a good sign.

For AIIDE in particular, I expect that my changes to the opponent model are key. I made the couple needed improvements of a previous post. The academic papers I found turned out to be unhelpful, and my changes are ad hoc, but they address the problems. If the opponent chooses strategies unpredictably, Steamhammer will too. If the opponent model doesn’t find a winning counter, it will explore more and more widely until it is randomly trying anything it knows, including openings which are otherwise not played in any context. On the upside, I’m hoping it will eventually hit on surprise counters to the toughest opponents. On the downside, in the worst case it will explore a lot of bad ideas, and the convergence time could be longer than the tournament!

Later today: Notice after Steamhammer 2.0 is uploaded to SSCAIT. Tomorrow: Defiler support in detail.