When an offensive lineman hits a defensive lineman to begin the play in football a low level concussive hit occurs and the brain of each player is impacted.
You play progressive maps where you either accomplish or fail at offensive or defensive tasks, such as lighting beacon fires or destroying trebuchets or defending your king from the attacking army.
Whisper it quietly, but some have even labeled Spain's previously much-feted tiki-taka style of play "boring" and claimed it is currently a more defensive tactic than offensive.