Starcraft AI blog

The BASIL stats page includes a table of unit types with how many of the type have been created and destroyed on BASIL in the last month. From this we can gain boring insights, such as that buildings are more likely to survive the game than units. But I also see a few interesting points.

Here are the basic units with their chances of dying. The cheaper the unit, the less likely it is to survive. Marines should have a lower chance to live than zealots, because sometimes you make marines only in the early game. To me, it’s not obvious that zerglings should have a lower survival rate than marines. Notice that zerg (48.5%) has a slightly higher overall winning rate than terran (47%). Maybe zerg mines more and burns more units overall.

What units had the best chance to survive? It seems that most unit types (leaving aside buildings and temporary units like eggs) are more likely to be destroyed than not. The table includes units with less than 40% destruction chance. The champion is the terran siege tank. I think that’s because when terran is able to make a lot of tanks, terran wins! The low death rate for dropships (but not shuttles at 45%) may mean that dropships maneuver more cautiously—reaver drops call for aggressive shuttle movement. It’s striking that, except for the tank, every unit in the table is a flyer. Most have ample hit points; tanks, vessels, carriers, queens, and guardians have long range and can stand off from the hottest part of a battle. Another possibility is that only stronger bots use high-tech units at all. Notably missing are the terran valkyrie and zerg devourer.

Some units you don’t expect to often survive the game, but sometimes they do anyway. My thoughts: If the scarab count includes scarabs made but unfired and remaining in the reaver’s inventory, the number seems too low; if it includes only scarabs in flight at the end of the game, it seems too high. Maybe it doesn’t count a scarab as destroyed if it was inside a destroyed reaver? That’s a lot of expensive unused nukes! Is the high number of active scans at the end of the game because some bot or bots scan for unseen bases when all targets are cleared? It’s too bad that only scanner sweep is included in the table. Other spells like psionic storm [an error; see comments], disruption web, and dark swarm are also represented as units; the difference is probably that scanner sweep is owned by the player, while other spell units are neutral.