Stalemate detection is a feature of melee games that ensures the game ends when no player can make progress towards victory.
A stalemate occurs when all players are unable to complete any of the following actions:
- Generate income
- Produce a unit
- Construct a building
- Research an upgrade
- Destroy an enemy building
After three (in-game) minutes, if no player has completed any of these actions, the game issues a final three minute warning. If these final three minutes elapse without a player completing any of these actions, the game ends in a draw for all remaining players. If a player completes any of these actions, the timer resets and play continues normally.
The conditions for a stalemate are precisely those described above. In particular, the following actions will not break a stalemate:
- Mine minerals or gas without returning them to a base
- Begin production of a unit, construction of a building, or research of an upgrade without finishing it
- Damaging but not destroying an enemy building
- Letting fire or creep deprivation destroy a building
- Destroying a non-enemy building (e.g., a neutral Supply Depot)
- Damaging or killing any unit
- A game can result in a tie without having a stalemate, if players/teams lose their last building simultaneously. This can occur if the last buildings are hit with a Nuke.