Starcraft AI blog

New bot Stardust (here is its BASIL stats page) is a development of Locutus by another name, by the same author, Bruce Nielsen. I don’t know why the name was changed, especially since the DLL name is still Locutus.dll, the name configured in the config file is still “Locutus”, and the SSCAIT comment says “it will only play as Stardust on SSCAIT. If downloaded it will play as Locutus.” That seems like a confusing choice. It is entered as Stardust in CoG 2020, though. Locutus classic is disabled on SSCAIT.

The most immediate change is that Stardust is updated to BWAPI 4.4.0. The DLL became smaller, perhaps due to dropping libraries.

It is usually difficult to notice changes in a bot’s play by watching games; a change may be obvious if you know what to look for, but invisible if you aren’t ready to see it. Nevertheless, I watched some Locutus and Stardust games and saw an unmistakable difference: Army maneuvering has been improved from UAlbertabot-style moving back and forth along a line to tscmoo-style keeping a constant distance from the enemy front. Keeping a constant distance means that you automatically form up into a concave when possible; when combat starts, whether in attack or defense, units are able to open fire almost simultaneously, with no maneuvering into position, so you do more shooting and less moving and kill enemies faster. It’s a big change and I expect it must have been in gestation for a long time.

There are disadvantages to the tscmoo style, but overall, Stardust’s formed-up armies should outdo Locutus’s jumble of units by far. I expect Stardust to reach a higher elo.

With a big change like that, there are likely smaller changes too that I did not see. I didn’t archive a recent Locutus version to compare, so I can’t draw a final balance. Comparing with the CoG 2019 version from a year ago, I can see some of the features added in the past year: Center proxies, a dedicated squad to chase down the enemy scout, the choke (as opposed to the wall) as a building location. But I don’t think any of those are recent additions.

My forecast: We used to think Locutus was scary. Now we’ll learn better.

Basic proxy skills were one of the major new features added in the current Steamhammer, version 3.0. It was preparation for the future more than a plan to earn cheesy wins: Steamhammer will need more skills before it’s any good at deciding when to proxy, and before it can execute well. And zerg doesn’t have many proxy opportunities in the first place, since it can only build on creep. Zerg can make a proxy hatchery, or versus another zerg (or in rare cases if there is neutral creep on the map) it can try an offensive sunken or offensive spore, that’s all. I was unsurprised when I checked a couple days ago and found that Steamhammer had recorded a total of exactly one proxy opening on BASIL, an ill-advised proxy hatchery in Microwave’s natural that went down for a quick loss.

Today I noticed another proxy attempt, and it’s a funny game: Steamhammer-krasi0P on Roadrunner. For background, #7 Steamhammer’s 60-day record against #11 krasi0P is 23-22, virtually even. So Steamhammer feels a need to keep experimenting to find better openings.

Steamhammer scouted at 5 supply, as soon as its first new drone hatched from the egg, which is necessary on a 4-player map if you want to find the enemy in time to drop a proxy hatch. The scouting drone went the wrong way while the overlord flew straight to the protoss base, but it made no difference; the drone scouted 2 empty bases and deduced the location of the enemy before the overlord came in sight of the nexus.

Krasi0P plays 2 related but different strategies, it either cannons up the exit of the enemy natural, or it cannons the entrance to its own base (and follows up about the same in either case). The 2 strategies are nearly identical from krasi0P’s point of view, but call for contrasting reactions from the opponent, “ha ha, it’s easy for me but hard for you!” In this game, krasi0P chose the forward cannons, so both sides are building in the enemy natural. It’s the Starcraft equivalent of Spy vs Spy; which will win this time? The picture shows Steamhammer’s spawning pool just starting as the cannons warp in; there is no hope of breaking the containment early.

Well, it was a funny start, but the rest is disappointing. The cannons were strong, but a hatchery is a production building and it can make units that go kill you. Krasi0P didn’t have any better defensive idea than to pull probes and lose them all. Once the protoss base was destroyed, the result was foreordained, even though Steamhammer becomes accident-prone when it has units on both sides of a contain: It blunderfully tries to join them into a single army. But all it had to do was kill cannons that could never be replaced, and it eventually did.

(By the way, are the pictures a good size? I have a bigger screen now and the images are not the same size as in past posts. You can click through to get the full size pictures.)