In the game

In Interactive mode, both sides start with a stronghold (which is usually unoccupiable on large maps). Both sides can only win by capturing more respawn points and killing enemies; in Assault mode, one side has one uncapturable respawn point, while the other side has most or all of the other positions. Some Battlefield games have an extension of Assault mode, in which the attacker must capture all other strongholds in order to take the defender's home base.
Other modes