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

Psycho (36 points): Complete the game in Rorschach mode.
Hero (36 points): Complete the game in Nite Owl mode.
Teamwork (36 points): Complete the game in co-op mode.
Thief (15 points): Find all abilities and pickups in Rorschach mode.
Detective (15 points): Find all abilities and pickups in Nite Owl mode.
Untouchable (11 points): Go unharmed for an entire level, without restarting from a checkpoint.
Turbo (11 points): Complete the game in less than 80 minutes in one session, without restarting from a checkpoint.
Vigilante (8 points): Eliminate 20 bad guys in 101 seconds.
Shield (8 points): Dodge or block 25 incoming attacks.
Strong Arm (8 points): Knock 100 people over, by throwing other people into them.
Retaliator (8 points): Perform 200 counter attacks.
Exterminator (8 points): Perform 250 finishing moves.