Complete any level in single player.
Unlocked: Offline
Game Master
20Complete the game.
Unlocked: Offline
Serious Sam
30Complete the game in single player on serious difficulty.
Unlocked: Offline
Complete the game in single player without firing a single bullet or shell.
Unlocked: Offline
Serious Run
15Complete the game in single player by beating estimated time on each level.
Unlocked: Offline
Complete Metropolis level in single player on serious difficulty without loading.
Unlocked: Offline
Pierce at least 10 enemies with a single cannonball.
Unlocked: Offline
Perfect Kill
10Kill all enemies in Karnak in single player.
Unlocked: Offline
Find at least 50 secrets in single player.
Unlocked: Offline
Complete any level in co-op.
Unlocked: Offline
Co-op Hippie
10Complete The Great Pyramid in co-op with blood option set to hippie.
Unlocked: Offline
Complete a co-op game on serious difficulty and extra enemy strength on 400%.
Unlocked: Offline