"Like Spit or Icehouse, players in Brawl do not take turns, instead either making a move or staying inactive as best suits their strategy at that moment. The game is fast-paced (games typically last a minute or two) but still has a fairly high level of strategy.
Each player has a different deck of cards. The object of the game is to win the most Base-cards by playing the most Hit-cards onto the Base before a Freeze-card is played on it. The game ends when a Freeze is being played on every Base in play. Player wins a Base-card if he has most Hits on his side of the Base. If both players have the same number of Hits on the Base, the owner of the Base-card wins the Base."
Source: Wikipedia, "Brawl (game)", available under the CC-BY-SA License.