Kill 10 enemies without losing your weapon.
Wield the pipe in single-player or co-op mode.
Wield the knife in single player or co-op mode.
Beat the game without using a special attack.
Beat the game without continuing.
Beat the first boss without dying.
Beat the fourth boss.
Beat another player in an online versus match.
Beat 10 opponents in online versus mode.
Complete an online co-op game.
Score 800,000 points in one game -- with Game Settings set to Hardcore.
Defeat Boss 'Jet' at the end of Stage 2 -- with Game Settings set to Hardcore.
