Starcraft AI blog

SCHNAIL players who try out Steamhammer often play a series of games one after another, and if they liked it they come back another day for more. I’ve watched enough of these series that I have a sense of the patterns they follow. Everybody’s different, of course, and Steamhammer’s play has random elements too. But often enough, a series with a terran or protoss opponent who is well-matched with Steamhammer more or less follows a prototypical sequence of four steps.

1. Get busted. Steamhammer is tuned against bots, where early aggression is successful, so it often starts out with a bust. Apparently many humans at this level are not quite prepared. Against terran it breaks in with zerglings or lurkers, against protoss with lings, hydras, or mutas. (Terrans are ready for mutalisks.)

2. Tighten up defenses. Players at this level figure out how to stop an incoming Steamhammer rush within a few games. That’s typically good for two or three wins before Steamhammer tries something else.

3. Get overrun by macro. Players at this level also tend to be too passive. Maybe macro and scouting and whatnot uses up their bandwidth, or maybe they’re used to being fine if they stay at home for a while. If the player goes active and begins attacks too late into the middle game, Steamhammer has already started to outmacro them and, even if it loses bases along the way, will finally win with hive tech.

4. Learn to attack actively. And players at this level don’t take long to understand how to react to zerg macro: Don’t let the zerg macro, but attack expansions aggressively. The new static defense code makes more sunkens at exposed outer bases against humans (not against bots), which helps them survive. But Steamhammer is not strong at defense, and players are fairly successful at taking the bases down anyway. After figuring this out, the human player will win games indefinitely, sometimes all games. If the two are closely matched, the games may be long and difficult.

Alternately, a terran may make one big timing attack into the zerg natural, and break through. Steamhammer can usually deter this plan versus protoss.

It seems to me that if you start out struggling to beat Steamhammer, and without using any special anti-bot tricks learn to defeat it, then you must have improved your play. Tight defense and active play are good. The same skills you polished to beat the bot will help you against other opponents.

Of course, many series don’t go this way at all. A player of different strength may get all losses or all wins. Several days ago one player played a long series of cannon rushes on the 2-player map Destination, first trying to push cannons from the side of the zerg base, then in later games switching to cannon the natural. The rush, after adding proxy gateways, often eventually destroyed the zerg main, despite being slowed by defenses, and units from the proxy gates were then able to move out and destroy more bases. But protoss was never able to stop zerg from expanding, and ended up losing every game, usually after defensive cannons in the protoss base suddenly fell. Steamhammer made many missteps, but I was pleased with the defense against cannon pushes. This was likely a player trying out the strategy for fun.

Here’s a short and surprising game from SCHNAIL, Steamhammer vs leftchange (T) on Heartbreak Ridge. Terran played an unusual and sneaky proxy. Steamhammer scouted it thanks to the anti-proxy overlord, and its first reaction was almost good; it did things right except for misplacing the sunken because sunken placement is optimized for stupid bot opponents. Steamhammer countered the empty enemy main, and soon neither player was able to mine. But there was a clear winner!

Today’s ASL 12 matches had another surprising and close proxy game with much better play, Soma vs JyJ on Polypoid. It starts at about 34:00 in this round of 16 group A vod with commentary by Nyoken and Scan. (I watched it “excluding restricted content” and didn’t miss anything that I noticed.)

The popular map Big Game Hunters (BGH) has been added on SCHNAIL. It is very different from standard maps: There are 8 start positions, the mineral patches and geysers have 10x or more the usual resources per item, the layout is irregular, and there are imbalances everywhere. Strategy is different than on a tournament map, and bots need different knowledge and tuning to play on it.

Nevertheless, when I noticed last night that BGH was added, I quickly enabled it for Steamhammer. It should be fun, and I expect that different bugs and weaknesses will show. Steamhammer has played 3 games on the map so far. It lost them all, but I did learn stuff—so far, so good.

From the game history, it looks as though Krasi0 is the only other bot to have BGH enabled. I see one game as far back as 8 September. I recommend the map for authors who have time to learn from their bot’s SCHNAIL games, or who just want more fun.

A Fastest map is also added. I did not enable that for Steamhammer. (The layout is different from Fastest AfreecaTV, the closest corresponding map in Liquipedia.) I think it is not as much fun, and without trying it I guess Steamhammer is not likely to work there. Again, Krasi0 seems to be the only bot to enable it.

Aside: If I were in charge, Big Game Hunters and Fastest would only be enabled for practice games. They should not be inflicted on human players when they’re being serious. But SCHNAIL allows it. I see ranked games in the history.

When I uploaded Steamhammer 3.5.1 to SCHNAIL, with new weaknesses, the bot lost 200 elo or more and also lost its popularity as a SCHNAIL practice opponent. I guess it’s not as much fun to play an opponent that sometimes plays fine and other times arrays all drones in front of the natural to make sunkens and then has no money to morph them. The bugs are fixed now. Elo is still lagging—elo changes slowly because there are not many ranked games—but Steamhammer’s popularity for practice returned suddenly. The players are getting information from somewhere.

In unrelated news, the name “Leta” is pronounced by some “Leeta”, by some “Layta”, and by some “Lehta” (which I guess is the correct one). In today’s ASL 12 round of 24 group E cast, Nyoken pronounced it all three ways in the space of a minute! Did anybody else notice?

Here’s a ZvZ SCHNAIL game where the human played an unusual strategy. It was a ranked game, so maybe the human shouldn’t be playing around... but they were clearly playing around. The game is Randomhammer - jki, appearing in the replay as Anonymous AI (rolling zerg) versus jk.

Randomhammer made an unfortunate choice of build, a hidden base with each base protected by a sunken. The goal is to survive a rush and hit back. Jki (who didn’t know at first that Randomhammer was zerg) went overpool then natural ahead of the hidden base, gaining an advantage from the start. And used the advantage ingeniously.

1. Contain Randomhammer to its main base with zerglings.
2. Get a spire.
3. Make scourge and repeatedly kill overlords. Overlords don’t cost gas and are usually a poor choice of scourge target, but since Randomhammer was already behind, it kept getting supply blocked and was unable to make enough units, air or ground, to break out. It didn’t help that it fought poorly.
4. Get lurkers too! The plan costs a lot of gas.
5. Win. If an overlord approaches to detect the lurkers, scourge it.

The picture shows the lurkers breaking down the hidden base. The lair is there because Randomhammer tries to morph the lair where it won’t be seen right away. Notice the human player’s much larger army supply.

In other ZvZ games, jki has played normal ZvZ strategies. The lurker plan was apparently an on-the-fly decision to have fun with Randomhammer’s poor start. Bots can’t do that... yet.

So, SCHNAIL believes I successfully updated Steamhammer back on 11 July, but it is still running the old version. It’s easy to tell, because of the orthogonal movement pattern and the jittering of Watch squad zerglings before burrow is researched. I’ve been too lazy to diagnose it and try again. Presumably I got something wrong in the zip file.

Nevertheless, I was surprised to see that Steamhammer is the #1 zerg on SCHNAIL as of now. Well, counting active zergs. The top zergs by elo are

1472 Steamhammer
1463 Chris Coxe (aka ZZZKBot)
1452 ZurZurZur
1440 Crona
1432 Monster
1384 Killerbot (aka Marian Devecka)

Chris Coxe is up there because of its rushy habits. I’m not sure why Monster and Killerbot are so far down; I would have expected them to do well against humans. Microwave is ranked above Steamhammer on BASIL, but below on SCHNAIL at elo 1280. In some cases, bots on SCHNAIL may be older versions. I know some bot authors update often on BASIL and rarely on SCHNAIL. Maybe they’ll read this post, update, and try to push Steamhammer back down where it belongs.

In other news, AIIDE 2021 registration is open. Steamhammer will be competing.

Hmm, has somebody been playing around a bit with their SCHNAIL installation?

This is from a replay recorded on the SCHNAIL server. I noticed a few other replays with similar map... issues.

Steamhammer (as the random-build Crazyhammer) played a particularly difficult game yesterday on SCHNAIL, a Crazyhammer versus kkt2108 (T) at server time 21-07-08 18:28:46. As background, this terran player had just lost a couple of games to randomly-selected zergling busts with different timings, and apparently decided that it would not happen again. It didn’t!

I trimmed out the minimap and everything below, so that you can’t tell who’s winning. But see the signs of tough combat: The zerg natural being replaced, the rubble of terran buildings at its entrance (at the very bottom edge of the picture), the zerg main nearly mined out and with destroyed buildings, a couple of terran stragglers still not ejected, and few zerg combat units visible though apparently zerg survived the battle that just finished.

Don’t miss the simultaneous attacks by both sides at the end.

Steamhammer-Joon is a funny game played today on SCHNAIL. (The player’s screen name is ZI7HMI and the game time was 21-06-30 08:48:50.) Steamhammer had played this opponent once before and correctly predicted cheese, so it started with 9 pool and a sunken in its main. Joon, being a crafty human rather than a bot, crossed this plan up by bunkering the natural below the ramp. At the time of this picture, the first terran barracks had lifted because it had started to burn, and the initial zerglings that escaped before the bunker were attacking SCVs.

Zerg was mining with more workers than terran, but was contained to its base—and terran sent most of the pulled SCVs back home, putting the human ahead in economy. Steamhammer kept sacrificing drones to the bunkers as it tried to expand (it’s on my list to fix soon with safe pathfinding), and losing overlords for lack of understanding of enemy visibility. But it also got lurkers, and terran was only just adding comsats. After a sharp struggle whose outcome looked uncertain at first, zerg broke its own natural—where terran had built a command center—and forced buildings to lift.

Now terran was far ahead in economy though with hands too slow to spend it, while zerg was ahead in army. Notice that terran is adding a starport while zerg is getting a spire. The zerg force, finding no buildings on the ground and unable to attack air, hurried across the map to the terran side. Immediately, Joon landed the buildings again, so that the drone which came down to expand could not take the natural but had to continue to another base to expand. Having crossed the map, lurkers forced the terran natural into the air and continued on to pillage the main, while terran quickly trained marines in the zerg natural and easily held it, restoring the containment—but with zerg already owning a base outside it.

In the picture you can see 2 vultures and a wraith, which proved of little value. Steamhammer scourged the wraith and a followup wraith (you can see the scourge in the production tab). At the opposite corner of the map, terran marines were supreme and Steamhammer chose a mutalisk switch, which was also of little value. The strategic situation completely reversed in a short time, with zerg ahead in economy and terran stronger in army. Steamhammer had taken the top center base, but was not mining there.

Steamhammer killed all SCVs in the terran main, left 1 lurker there to finish cleaning up, and returned the other 3 to visit the terran complex at the zerg natural. At the same time, the strong terran infantry easily broke the sunken in the zerg main, which had been waiting there since the early opening, and set about their own cleanup. Base race!

A crazy game, and a close one. Both players had opportunities to turn events in their favor at multiple points. I won’t spoil the end, though it’s predictable if you know how terran-zerg base races go. You can watch it to see.

Here’s a fun SCHNAIL game, Steamhammer-HitHat (screen name Joongwan). Steamhammer had played this opponent before, so it had an idea of what to expect and made an early sunken. The sunken is misplaced. The misplacement is better against other bots than correct placement, but you’ll see in the game why I call it a misplacement! After learning by the loser, the next game went differently. Another interesting game is this one on Fighting Spirit against a different opponent.

I’m not sure why there are separate screen names and game names. The website comes with an API that gives the screen name with replay, and the replay has the game name, so no information is hidden. Still, people use the feature a lot, so it must have appeal. Are names that much fun? I’m guessing it was a feature added at the request of players. I sure wouldn’t have thought of it.

Steamhammer 3.5.1 is progressing, though slowly. Since my energy ran down, I stopped working on my plan of using Steamhammer’s new opening data. After seeing many SCHNAIL games, I’m mostly making changes to improve Steamhammer’s play against humans. Humans know a lot of tricks that bots don’t know, and they’ve uncovered weaknesses that I want to fix. Better is better, even when it may not show against bot opponents.

I rewrote Steamhammer’s crufty old code for deciding when, and in what bases, to place sunkens and spores. Unlike bots, humans are quite good at attacking vulnerable bases first. (Steamhammer makes an attempt to get this right. Most bots don’t try.) I was running the first tests, demonstrating that it worked in a couple of simple situations, when I realized that I should have generalized it for all races. Terran and protoss desperately need the skills: Make mutas and win because terran doesn’t add turrets; make DTs and win because only one base gets turrets or cannons for detection. I’m not only working slowly, I’m thinking slowly.... I rearchitected it and rewrote nearly all the code a second time, in a new StaticDefense class. It’s cleaner and more capable, and should be easier to adjust. It’s just now ready to get back to testing.

Humans make very different opening choices than bots. Most stick with general-purpose safe openings; a few specialize in cheese. I don’t have any way to collect SCHNAIL opening data, so I started a new file to hand-write an anti-human configuration. I didn’t fill in much of it yet, but I’ll get to it.

I expect my tweaks and new features to help somewhat on SCHNAIL and a tiny bit on BASIL. But we’ll see.

My energy is low, but I’m still working on Steamhammer and checking out games. Crazyhammer is Steamhammer configured to choose purely at random from its library of over 200 zerg openings. It plays only on SCHNAIL, and only practice games, because it’s just for fun.

Crazyhammer doesn’t get many games, and it loses a lot because its builds are often hilariously inappropriate. As you’d expect! Today Crazyhammer played a fun game against terran TeChRapy on Fighting Spirit. Crazyhammer randomly chose its queen rush build, which will happen about 0.45% of the time—this is the first time I’ve seen Crazyhammer play it in a real game, though Steamhammer did give it a try versus Stardust in AIIDE 2020.

In the queen rush, Steamhammer makes 6 queens early on and researches broodling. It’s hard to think of an opponent plan that it counters. I don’t have the strength to take pictures and do the blow-by-blow, but here are a few points you might like to notice.

• Watch the swoopy way the queens fly around. It was the simplest idea I thought of to keep the queens apart so that they don’t often select the same target. It didn’t work this game! At about 9:30, 4 queens simultaneously and from different sides ensnared the same group of marines. I should bite the bullet and implement proper spell target tracking.

• Techrapy went with multiple barracks, no tanks. Nothing was worth a broodling, and the queens were useless at first.

• Crazyhammer reacted by researching ensnare and adding lurkers, both useful against marines. Techrapy got tanks against the lurkers, and then the queens had a broodling target.

• The queens sucked at staying safe. One of the 4 ensnaring queens retreated forward instead of backward, and got shot down. Later, 2 queens in a row flew into turret range and died trying to snipe the same tank.

• On the upside, the fast queen’s nest meant that the hive was not too slow. Defilers helped.

In the following game, Crazyhammer started with 8 hatchery 7 pool, and Techrapy won easily. Terrans at this level usually play a barracks-expand build which is safe against zergling openings, given scouting and a few easy reactions. Certainly safe facing Steamhammer’s level. In the queen game, maybe Techrapy was confused and made overcautious by the “unconventional” (aka bizarre) build.

Queens showed poorly this game, but I’ve been surprised how often they are successful. When terran turtles hard, Steamhammer’s queens can be as valuable as its defilers in breaking the shell. Knowing that queens are in play tends to make terrans spend on air defense and move around more slowly and cautiously. And I know what I need to do to make them more effective.

In 2017, I posted breaking scouting assumptions about a crazy trick terran can play: Lift off the initial command center and land it elsewhere, so that the opponent does not scout you at any starting base.

Today will go down in history, because somebody played this trick versus Steamhammer on SCHNAIL.

The game is LiberTY_ vs Steamhammer on Fighting Spirit, at 21-05-19 08:40:04 in SCHNAIL server time. Let the timestamp be forever honored in memory. Some background: Liberty (under a couple of related names) has played many practice games against Steamhammer, having some trouble at first but steadily improving and now winning nearly all games. This is someone who has learned Steamhammer’s weaknesses and has exploited them with increasing efficiency. Maybe the game was to accept a handicap and make Steamhammer a serious challenge again. Or maybe it was just a fun try to see if the bot would do something silly in the silly situation.

Liberty started in the bottom left. Here the command center is approaching to land in the bottom middle base. See the worker counts—lifting off your base interrupts mining for a long time in the critical early game, so it is a severe setback. Terran has no chance unless the trick breaks Steamhammer somehow. Steamhammer’s overlord is only halfway across the top of the map on its scouting trip, so it would have been possible to lift off later, losing less ground. A little less.

Steamhammer scouted the bottom right base last, so it believed that was Liberty’s start base. The drone scouted it thoroughly, over and over, even after finding it empty.

Wasting time with the scout drone was Steamhammer’s only real misreaction to the trick. The scout manager does not update its idea of what location needs scouting merely because the location is empty, but the information manager understands that no enemy base has been found. The initial 6 zerglings set about scouting the map for the terran buildings that must exist, checking base locations first (including bases that were already scouted). At about 5:30, a watch squad zergling arrived to keep a watch on the empty enemy “main”, and the scout drone could return home. By coincidence, at the same time, the now more numerous lings found the terran encampment and did some damage.

This was not a scouting squad, it was a combat squad, and it was only scouting because it hadn’t found a place to attack. The lings had speed and there were only 4 marines. The game could have been over right there, but Steamhammer controlled its units poorly (in part because of crummy code trying to join clusters that became separated), and terran suffered only moderately.

But zerg had made no fatal mistakes and was too far ahead. With little room on the tiny mesa for ground production, Liberty chose wraiths. The first 2 wraiths arrived at a zerg base and were scourged before they could do damage. Soon the wraiths did better with cloak, but paper airplanes were not going to stop any zerg army for long.

Steamhammer’s reaction was about as good as I expected, and easily good enough. Does your bot survive this crazy trick? Probably! The only critical skill is the ability to notice that an enemy base is not where you “knew” it was, and you need that skill in case an enemy command center lifts off or burns down, which can happen in a normal game.

The number of games on SCHNAIL exploded recently. I assume it’s related to the new SCHNAIL stream showing random replays of past games. Is there another source of publicity that I didn’t notice?

Nice job, Sonko and Bytekeeper! I especially like the viewpoint switching and the treatment of fog of war in the replay viewer. Of course, it is a universal constant that there is room for improvement. I wonder: Are new viewers able to tell the bot player from the human player? I can tell easily, but I already know all the bot names.

It’s been a while since my last post, but I’m still working, however slowly.

In today’s SSCAIT report “By the skin of your teeth”, the last game of the broadcast is the same game I analyzed last month, Chobo-Steamhammer on Python, the corsair-reaver game, with commentary by the player himself. His analysis of the game seems similar to mine, except of course with insight into the human player’s thoughts rather than the machine’s.

The SCHNAIL web site was updated as promised, and looks much prettier. On the leaderboard, “Download” is still spelled “Dowload” though.

Today is an interesting game from SCHNAIL, Chobo (P) vs Steamhammer on Python. Chobo played corsair-reaver with mass reaver drops to destroy bases and an eventual switch into carriers, a classic strategy I have never seen used against Steamhammer. It’s a demanding strategy for both players. Protoss must be fast and aggressive with drops, never leaving its expensive forces long at home because zerg grows back fast. And zerg must cope with the overwhelming splash damage of reavers on the ground and corsairs in the air—the units may not work against Monster, but they are deadly against Steamhammer. Classic zerg play against corsair-reaver includes burrowed zerglings around the map to see the reaver drops coming, a skill that Steamhammer does not have.

Corsair-reaver depends on a heavy force of tech units, so it launches slowly. Chobo curiously did not take the natural, but blocked the ramp with 2 zealots and a dragoon while teching, then took the nearby island base—which, by the way, I think Steamhammer never discovered. Steamhammer luckily started with a 3-hatch strategy before it scouted the protoss base, so it did not fall behind right off. A one-reaver probing drop did light damage at the zerg natural, then the reaver relocated to the morphing zerg third to try to prevent it. But scourge chased the shuttle away and hydra-ling chopped the reaver. Chobo learned a little caution.

Seeing the reavers, Steamhammer elected to make mutalisks despite the corsairs. It does understand the tradeoff risk... in a vague way. Soon protoss moved down the ramp to take the natural as a third base. By this point, Steamhammer was worried by the powerful-looking protoss force and went with army over economy, starting to fall behind. Chobo tried a 2-reaver drop at the zerg third and killed the defending sunken, but the drones burrowed and protoss left rather than risk the reavers. Still, with 2 bases and another coming versus 3 undersaturated zerg bases, protoss was ahead. Chobo dropped again, again killing the replaced sunken and again retreating. Seeing the drones instantly burrow and unburrow as the reaver appeared and disappeared must have been amusing.

At this point I think the human player began to go wrong. Chobo made defensive cannons and moved by air to take a 4th base, dedicating reavers and adding ramp cannons for its defense. Chobo was perhaps concerned about APM and reaction speed, limited resources if you’re human. But a human can’t outmacro Steamhammer without keeping pressure on. The reavers in speed shuttles are highly mobile. If protoss wants to take another base, I think it’s correct to airlift in minimal defense and rely on the main force to fly to the rescue in case of trouble. In case of no trouble, those reavers want to be blowing stuff up, or at least threatening to. Anyway, a zerg base was morphing below the new protoss base, and the hatchery did not last long. But Steamhammer, seeing more cannons and not seeing more army, correctly concluded that it could make drones and tech up. At the time of the picture, defiler consume is researching.

Steamhammer poked the protoss main with its mutalisks, and Chobo responded by chasing the mutas back to the zerg base and eradicating them, with minor corsair losses. Steamhammer does not understand that air units can scatter and keep fleeing, it believes they have to make a last stand to defend the base. Zerg was reduced to 15 army supply versus 52 army supply for protoss.

It didn’t matter. Zerg had the economy and soon reached its drone limit of 75 (this was Steamhammer 3.4.8, not 3.5 which has a limit of 65). When the corsairs and shuttles moved toward the zerg army, they were plagued and then ensnared, so that the outnumbered mutalisks (11 corsairs with attack +2, 10 mutas with carapace +2) held the upper hand. Protoss dropped the zerg third again, this time with mass reavers and disruption web, and eradicated it. With an observer, the reavers wiped the burrowed drones too. Steamhammer countered in the protoss natural with dark swarm and zerglings and returned the favor. In the picture, Steamhammer has realized its mineral excess and is adding hatcheries to burn it off—and meanwhile, the overloaded human can’t keep up with macro (watch the APM figures).

Carriers arrived and there was more fighting, but the strategic position was decided. Drones and hive tech beat reavers and carriers. The picture is shortly after a base full of drones was destroyed, but as soon as the drones visible in the production tab finish, Steamhammer will have re-maxed its drone count.

I wish the game had lasted a little longer, so that I could see how well Steamhammer’s endgame scouting and clean-up of islands works. It theoretically has the skills, but so few opponents take island bases that they are untested in real games.

An entertaining game. A lesson for zerg bots: Defiler skills count! Steamhammer needed both plague and swarm to win. A lesson for human players: Keep the pressure on! There is one regular SCHNAIL opponent for Steamhammer who seems to enjoy playing tower defense as terran: Stay alive as long as possible with bunkers and tanks and turrets. The two have played dozens of times, and Steamhammer has won every game. Defending does not keep you alive, attacking keeps you alive.

A few unrelated things I’ve noticed on SCHNAIL.

bad bots

There are a couple of bad bots that don’t start up. One is named “test”. Since the starting elo of 1500 is near the top elo for bots, and the elo falls slowly since nobody plays many games against a bot that doesn’t work, in ranked play the bad bots tend to be matched against the stronger humans. That’s unfortunate.

human habits

In practice games, most humans seem to have favorite bot opponents, and don’t experiment widely. That’s interesting, and to me a little surprising. Most pick opponents that they usually lose to. I think either they are truly practicing, or else they’re taking it as a challenge. The strongest humans don’t have bots that they usually lose to, though.

I have the impression that there have been more ranked games over time, as a proportion of all games. Maybe players are getting familiar enough to feel comfortable with it. Many humans choose practice games every time, though, which is of course a perfectly good choice.

It’s curious, but human games are more stereotyped and less varied than bot games. At least at this level on SCHNAIL. (It’s not so at the highest level of human play.) Most humans on SCHNAIL seem to play the same base strategy every game, like the bot SAIDA does, with adaptations to what they’ve scouted.

Humans quit the game before any fighting in a surprising (and irritating) proportion of games. It’s impossible to know how much it’s due to “Oops, I messed up my split, try again,” versus “I’d better take this call,” versus “ack, why’d it freeze now?” From my point of view as a bot author, these are noise games that make the data harder to interpret.

Steamhammer’s play

When Steamhammer wins, it’s not due to better strategy (it’s worse than humans), or better tactics (it’s far, far worse), or better micro (better in some aspects, but overall worse). It’s occasionally due to a rush, zerglings or lurkers breaking in by surprise, but not often; humans are better at adapting and more resilient in defending than bots. Usually it’s due to better macro: “I lost this base, I lost that base, I didn’t kill any bases of yours, but I’m still ahead in workers. Say goodnight.”

Steamhammer’s inability to foresee an enemy army’s intent is a severe weakness. “Your army is over there, near my expansion? It’s out of position, I’ll move right up in front of your natural. Wait, you’re attacking my expansion now? Run run run to defend! Oops, too late.”

In games versus terrans, it’s clear that Steamhammer is now stronger with lurkers than with mutas. Lurker play is still crude, but the recent improvements have paid off.

gg when losing

As mentioned in the post the HumanOpponent flag, Steamhammer behaves a little differently when facing a human opponent. In particular, it gives up much earlier when losing. The rule is explained in the old post.

When I wrote that surrender rule, I doubted that it was tuned well. I have been pleasantly surprised, because it works great. In actual games, Steamhammer only surrenders when it is truly losing, and the timing is almost always reasonable: Late enough that it is also clear to the opponent that Steamhammer is losing, and early enough not to waste too much human time. I wish everything worked that well!

Next: I played around a bit with the SCHNAIL api. It’s easy to extract data in JSON format. I want to analyze it a bit.