Custom refers to a multiplayer game arranged through GPGNet. Custom games do not affect a player's rating or rank.

The player that creates a custom game specifies all aspects of the game, including map, number of players, and game options. The creator can either protect the game with a password to ensure only specific players may join, or he may leave it open to anyone who wishes to join. As other players join, the game creator can kick players out of the match if they are known to be abusive, have unacceptably high pings, have computers with poor performance, or are otherwise unwelcome.