Starcraft AI blog

Protoss Pinfel is reactivated. It is scoring few wins, but I enjoyed watching its games. It defeated Microwave and had narrow losses versus Johan Kayser and versus McRave. It’s a good result for a new bot made from scratch.

Pinfel makes the most extreme form of all-in attack. It brings every single unit, including all probes; the attack wins or loses, and that is that. Good micro counts but other skills do not come into play, so it is a fine choice for a new bot which doesn’t have many skills yet. It will encourage the bot author to work on micro, which will pay off even if the bot switches to a different strategy later.

An all-in attack can be less extreme. “All-in” means that the attacker is deliberately setting itself far back in order to make a stronger attack, and will be losing if the attack is not successful. The attack is successful if it harms the enemy enough to make up for the setback. It’s a threshold: Do this much damage or probably lose.

The goal of going all-in is do fatal damage, so if you’re bringing workers it rarely makes sense to bring only a few workers. (Exception: A zerg versus zerg sunken rush.) Bring many workers. If you bring all workers, your damage threshold is: Wipe out the enemy entirely. Pinfel’s narrow losses against Johan Kayser and McRave came when it almost but didn’t quite meet the threshold; the enemy’s last two or three surviving units were enough to turn it around.

If you leave some workers behind, your damage threshold is lower. You’ll have fresh production, though it will be slow, and you can still win if a few enemies survive. Pinfel would likely be stronger if it left a few of its probes at home. Using the few workers to best effect requires more skills, but simply making extra units as the cash comes in is easy and gives you a chance if the enemy narrowly survives.

If an all-in attack catches an enemy with its army out of position to defend, the enemy may decide to go after your defenseless base instead, triggering a base race. If you’re planning to all-in, it makes sense to prepare: Build a pylon, or supply depot, or zerg extractor, in some hard-to-scout spot on the map. You can lose your entire base and still win if the enemy doesn’t find your hidden building.