ACHIEVEMENT - HOW TO UNLOCK Pipe Wielder (5 points) - Wield the pipe in single-player or co-op mode. Knife Wielder (5 points) - Wield the knife in single player or co-op mode. Psycho (15 points) - Kill 10 enemies without losing your weapon. Perfect Boss (10 points) - Defeat the first boss without dying. Fourth Boss (10 points) - Defeat the fourth boss. First Versus (10 points) - Defeat another player on Xbox Live in a versus match. Online Warrior (5 points) - Defeat 10 opponents on Xbox Live in versus mode. Online Co-op (10 points) - Beat an online co-op game. High Score (25 points) - Score 800,000 points in one game with Game Settings set to Hardcore. Kill Jet (30 points) - Defeat the Boss "Jet" at the end of Stage 2 with Game Settings set to Hardcore. Hard Win (35 points) - Beat the game without using a special attack. Perfect Win (40 points) - Beat the game without continuing.