Complete an online co-op game.
Beat 10 opponents in online versus mode.
Beat another player in an online versus match.
Beat the game without using a special attack.
Beat the game without continuing.
Beat the fourth boss.
Kill 10 enemies without losing your weapon.
Beat the first boss without dying.
Wield the pipe in single-player or co-op mode.
Wield the knife in single player or co-op mode.
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.
