Accomplish the indicated achievement to get the corresponding number of 
Gamerscore points:

  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): Complete 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): Complete the game without using a special attack. 
  Perfect Win (40 points): Complete the game without continuing.