The object of the game is to destroy your opponent. Whoever dies first loses.
The ways to die are:
Go offscreen for more than 1 second
Have your heart (purple box) fall out, or have it only connected to a couple of pieces
So you need to get your opponent to die somehow. You could beat him up or make him fall offscreen, or you could use your SPECIAL POWERS. Here are the special powers for each player and the ratings:
9876 = 9 pot. power, 8 diff. to dodge, 7 safety to self, 6 area of effect
(9) means also has poss. to kill foe, but only in certain conditions
(0) for safety to self means it could possible hurt you later
P1 (Arrow keys) (All numbers on NUM PAD):
9: Ball drop (boulders fall from sky) 8756
8: Spike fire (shoot spikes from ground, can impale foe) (9)458
7: Airbag (fires your airbag; use to get out of debris) 0093
6: RainbowBallo'Death (ball rolls and crushes stuff under the roof) 9183
P2 (WSAD)(All numbers above letters):
9: Cymbal clap/drop (hard to explain) 8992/(9)992
8: Floor drop/catapult (drops floor or catapults it...) (9)958/7985
7: Airbag (see above) see above for rating
6: Destroy ceiling (removes an important safe spot!) (9)9(0)5
5: Dodge explode (blows up the dodge

) 4992
Have fun!
CREDIT TO ivanoski FOR THE DODGE