Complete a co-op game on serious difficulty and extra enemy strength on 400%.
Complete The Great Pyramid in co-op with blood option set to hippie.
Complete any level in co-op.
Complete the game in single player without firing a single bullet or shell.
Complete the game in single player by beating estimated time on each level.
Complete the game.
Pierce at least 10 enemies with a single cannonball.
Complete any level in single player.
Complete the game in single player on serious difficulty.
Complete Metropolis level in single player on serious difficulty without loading.
Kill all enemies in Karnak in single player.
Find at least 50 secrets in single player.
