Starcraft AI blog

Locutus is doing great. What I find more interesting is that Microwave is also doing great since its update yesterday. In particular, Microwave seems to have improved enough to beat Iron consistently. I thought the most interesting game was the most recent one.

Furthermore, Microwave played more than one opening against Iron in its recent winning streak. Its favorite, though, seems to be 9 pool with a fast 2nd hatchery. The game plan has not changed much, only the execution is improved. Early zerglings hammer on the terran wall, occasionally breaking it down but usually only sapping the terran income. The lings don’t care if the wall is open, or if they come under fire, they only want to hit those supply depots. Microwave defends against the vulture runby with sunkens up front plus a sunken in the main. Iron usually appears surprised by the sunken in the main and fails to cope with it. Microwave follows up with hydralisks and later mutalisks, switching flexibly between hydras and mutas and preventing Iron from gathering its forces—especially targeting tanks so that they don’t build up to large numbers. Eventually Microwave reaches a critical mass of hydras and wins.

Even if you are as good as Iron, that is what happens if you always play the same and don’t update for a long time.

Locutus and Microwave are both Steamhammer forks. I’m pleased that they’re doing well. I see it as partly my success, too.

backward games

I added a zerg-versus-zerg 12 hatch opening to Steamhammer. It’s the greediest common ZvZ opening, so Steamhammer only plays it when the opponent model expects that the opponent will also play a hatchery-first opening. But look what happened: In a test game today against Microwave, Steamhammer opened 12 hatch and Microwave played its 5 pool opening. Steamhammer saw it coming only after the spawning pool was started; all it could do was start a sunken as soon as possible. Microwave’s zerglings tore down the natural hatchery first, and that was enough time for the sunken to finish and 4 zerglings to hatch, just enough to hold the rush. Steamhammer had a huge drone advantage, went up to 3 hatcheries, and smashed down Microwave by brute force while fighting right in the face of Microwave’s emergency defensive sunken. That’s the way to play!

It’s no wonder that pros, with their much stronger defensive skills, are so willing to play a greedy opening like 12 hatch in ZvZ.

Microwave’s 5 pool, by the way, is a clever build. Microwave builds a second hatchery at its natural to keep the zergling numbers up, and if the pressure doesn’t work out it drones up and switches to mutalisks. The opponent has to keep playing well to stay ahead. In a different test game, Steamhammer predicted the 5 pool and played an anti-rush opening which held the zerglings easily—then Steamhammer lost despite its advantage because it didn’t tech fast enough: The lair finished, and it decided to build a macro hatchery before the spire; the spire finished and it decided to build a third base before any mutalisks.... That’s not the way to play!

Steamhammer 1.4 is frozen

Steamhammer is feature-frozen for the 1.4 release. I will keep on fixing bugs and minor weaknesses (lair finished...) and tweaking the configuration, but I won’t start anything bigger that might delay the release, though there are plenty of temptations. I should be able to upload within a day after SSCAIT reopens for submissions, and release after another day or so once I can see that I didn’t break anything obvious.

Steamhammer 1.4 is substantially stronger than the tournament version in some ways. I think it is especially improved at transitioning out of the opening in ZvP. It will start off slowly on SSCAIT, because it will have to learn for itself how to beat a number of opponents that it currently beats by hand configuration. Also the opponent model has weaknesses and blind spots that are sure to cause some surprises. Still, if I didn’t mess anything up, Steamhammer should at least keep up with the competition and maintain a place near the top. Its play continues to grow more complex and interesting.

the game info display

As an example of a minor change, I have updated the game info display that Steamhammer can draw in the upper left corner.

If we have decided to steal gas, whether in the opening build order or in the opponent model’s auto gas steal decider, the strategy line adds + steal gas.

Opp Plan is the opponent’s plan. It is often Unknown. If the opponent model has predicted the opponent’s plan and the plan recognizer hasn’t verified it yet, we get the orange word expect. The opponent model tends to be overconfident about what it expects. When the plan recognizer thinks it knows what is going on, expect disappears and the recognized plan shows. The plan recognizer also relies on inadequate information, but at least it looks first. Steamhammer uses both the expected and the recognized plans, to a limited degree, for different purposes and with different levels of confidence.

The Time: line gives the game time in frames and in minutes:seconds. The minutes:seconds display is both more compact and easier to read than the original XXm YYs display. Then come the mean and maximum time spent per frame, in milliseconds, so we can start to get an idea of when things are slow.

Steamhammer and Microwave are both rated close to 2200 at the moment, putting them in the top ranks on SSCAIT. There is a big pileup at that skill level; only Krasi0 and Iron are significantly stronger. And yet a few days ago, Steamhammer and Microwave struggled against each other in a game with so much nonsense play that I was raging at them the whole time, sitting on the sofa with a laptop and shouting “Why are you doing that? DON’T DO THAT! Aargh!” Facepalm. There is so far to go.

It had better be true that you learn the most from mistakes, because there are a lot of painful mistakes here that are hard to look at.

The game is Steamhammer vs Microwave on Icarus. Steamhammer opened overlord, then hatchery, spawning pool, and gas all on 9/17. Microwave opened spawning pool on 9 and gas. Steamhammer’s worker defense is poor and the 9 pool will win if Microwave sends its zerglings immediately in the right direction. Microwave scouted with a drone and found Steamhammer’s base on the second try, which was too late. But Steamhammer's zerglings were distracted by the scouting drone, and Steamhammer did well to survive with 2 drones lost. Microwave could have won on the spot if it had scouted with an overlord, or if it had inferred Steamhammer’s base location when it saw Steamhammer’s overlord.

Steamhammer continued to chase the scouting drone. Urgh. The misbehavior is still there because I haven’t found an easy way to prevent it that doesn’t cause other bad behaviors—if it ignores the scout, that’s bad too. My plan to fix it requires time and care, so I’m putting it off for now. Anyway, moving the zerglings out of position offered opportunities to Microwave to stab into the mineral line, but Microwave played overcautiously and did not. Aggressive play would be to rush all zerglings in to wreak havoc, then try to escape when Steamhammer reacts, so that you don’t lose to the counter. Safe play would be to detach 2 to 4 zerglings to try to catch a drone, while keeping the others back for defense; if the raiders are surrounded and lost it is no terrible setback, and if they kill a drone that is an edge.

Steamhammer finally killed the scout and started to realize the advantages of its build. With 2 hatcheries from the start, it was far ahead in zerglings, and Microwave was forced into static defense. Microwave added 2 sunkens in its main... and expanded, so then it added 2 more sunkens at its natural. 4 sunkens are a fatal expense, and Steamhammer was miles ahead. In the picture, Steamhammer has so many more zerglings that it should have attacked immediately.

There are a lot more mistakes in the rest of the game, but the story is getting tiresome. Steamhammer refused chance after chance to widen its lead or win outright. It held back when it should have attacked. It built an ultralisk cavern and researched the expensive ultra upgrades, then did not build a single ultralisk until they lost their value. It made guardians and devourers and used them wastefully (partly because it hit a bug which assigned units to the wrong squads). It became so lax in applying pressure that Microwave caught up in economy. You can watch the end of the game yourself, if you can stomach it.

It was much smoother than past Steamhammer games that I have blogged as disastrously bad. The bot is slowly getting more solid.

Two strange events.

let’s put the expansion right there

In a game versus Krasi0, Steamhammer decided to go three hatcheries before spawning pool. It’s a greedy opening, a sensible choice against Krasi0’s slightly less greedy opening. Of course, when you’re trying to win by greed you tend to scout late, so when it was time to place the 3rd hatchery, Steamhammer did not know where Krasi0 was. The expansion drone walked past a bunker under construction and started the hatchery in the terran natural.

Steamhammer had the good sense to cancel the morphing hatchery before it died, but still.... Opening build: Failed.

When the enemy base location is unknown, MapTools::getNextExpansion() is supposed to choose the free expansion closest to home by ground distance. It should have chosen the 6 o’clock base, not the enemy natural. It’s a bug.

wait, is this the same game again?

Steamhammer played against Microwave 2 times in the last 2 days: Yesterday’s game and today’s game. Both games were on the map La Mancha, which is a little surprising since there are 15 maps. Both games had the same positions, Steamhammer in the upper left and Microwave in the lower left. OK, it could happen sometimes. And in both games, Steamhammer played its overgas 11 pool opening, a risky opening that it is set to play just under 1% of the time.

That does not happen! This is a coincidence that should come up 1 time in 18,000, more games than Steamhammer has played. Did somebody take control of the random number generator?

Microwave was blue in both games, but Steamhammer got different colors. Whew. The games were similar, as you might expect. Microwave played overpool and was almost but not quite able to capitalize on its earlier zerglings...

... then lost to the fast mutalisks that Steamhammer got by going gas first.

A third game today between the two bots was completely different. That’s how it’s supposed to work.

The SSCAIT news is that McRave and Microwave have been steadily climbing up the ranking. I’ve been watching it happen for a while. Just recently McRave edged past Steamhammer in elo, pushing Steamhammer down from #4 to #5. Today Microwave has moved ahead of McRave. The 3 bots seem quite close in strength for now.

Maybe the two authors would like to comment on their improvements?

According to my machine learning algorithm, the important common factor between protoss McRave (made from scratch) and zerg Microwave (a Steamhammer 1.o fork) is the -ave name. I speculate that there may be a connection with Aves, the birds. In any case, the hypothesis suggests that PurpleWave may be the next climber, and I hear that plans have been laid.

Now back to work. My tactical changes have introduced some new misbehavior that must be addressed, and not with “hello, misbehavior.”

SSCAIT’s mini-tournament is not quite finished as I write.

The irritating news of the tournament: Steamhammer played 2 tournament games versus XIMP by Tomas Vajda, plus one game shortly before the tourney, on the same map (Benzene) with the same starting positions (protoss on the left, zerg on the right). Just how random is it? The 3 games were nearly identical, down to individual army movements, and Steamhammer lost, as it should have, because it doesn’t understand map blocks and couldn’t finish its opening build. Sometimes luck hits like a truck.

The interesting news of the tournament: Tscmoo protoss is doing surprisingly well, including against opponents that it has a mixed record against. Did its opening learning, which was reset in December, finally gather enough data to make good decisions? We’ve seen before that Tscmoo brings its best against strong opponents. What’s behind that?

A razor close game between Steamhammer and Microwave on Python: Steamhammer opened with overpool into fast spire, while Microwave went overpool with zergling speed and mass lings, leading to a later spire. Steamhammer made 2 sunkens with its spire. When Microwave’s zergling numbers grew large enough, it defeated Steamhammer’s lings and pushed in; the sunkens and 2 fresh zerglings were barely enough to hold them off. When its faster second hatchery came online, Microwave attacked again; the second wave killed the sunkens and a couple of drones, but the first mutas cleaned up. The third wave left 2 Steamhammer drones alive, and by then Microwave’s spire was up too, and soon Microwave destroyed Steamhammer’s spire. Steamhammer scourged an overlord, which delayed Microwave just enough. Here Microwave is adding drones when it should be replenishing its army.

If you make too many drones in ZvZ, you die. Microwave was behind in air power and did not keep the pressure on. Steamhammer killed another overlord, outmicroed the scourge...

... and brought down the excessive number of drones while defeating mutalisks that spawned one at a time. Microwave helped by transferring drones from its natural to the main where the mutas were. Microwave might have held if it had gotten up a spore colony in time, but it was too late.

The long-awaited Microwave by MicroDK was uploaded today. Congratulations to MicroDK on an outstanding start, 11-4 as I write including a win over #1 Iron.

One of Microwave’s favorite moves seems to be walking a line of sunkens toward its ramp. It’s kind of cute, and I imagine it’s effective against many bots.

Though Microwave is a fork of Steamhammer 1.0, it seems to borrow some behaviors from later Steamhammer versions too. I noticed that it made 2 evolution chambers but only used 1 of them, a UAlbertaBot limitation. I mentioned the fix to that problem in a comment to AIL, but let me bring it out front: In ProductionManager::getProducer(), add the lines

		if (unit->isUpgrading())   { continue; }
		if (unit->isResearching()) { continue; }

alongside the similar checks.

It also seemed to stumble into bunker range. Steamhammer 1.1 and later do that less often because they understand the range of a bunker. I don’t think of it as a bug fix; it swaps one poor behavior for another that is usually less bad. In Squad::needsToRegroup() where it calculates range, I changed the call to

          int range = UnitUtil::GetAttackRangeAssumingUpgrades(eui.second.type, u->getType());

which I rewrote to pessimistically assume that enemy units have their range upgrades. It also adds in the range bonus of a bunker. UAlbertaBot originally ignores both. Someday I’ll detect these silent upgrades and whether the bunker is loaded, but not yet.