Successfully complete the Challenge Brick level with a "Gold" rank to unlock the Brick weapon in multi-player mode.
Faster reloads
Some guns have slower reload times than others. Instead of pressing Reload, press Next Weapon quickly followed by Previous Weapon (or vice versa). When you switch to a new weapon and go back to it, the weapon will automatically be reloaded.
Unlock Ample Sally Character
Get a silver or better in the 'Take 'Em Down' challenge in Challenge Mode.
Unlock Badass Cyborg Character
Get a silver or better in the 'Badass Buspass Impasse' challenge in Challenge Mode.
Unlock Big Ears Character
Get a silver or better in the 'Escape From NeoTokyo' challenge in Challenge Mode.
Unlock Cardboard Characters
Beat the game on Easy difficulty.
Unlock Characters in Arcade Mode
Earn a Gold medal in "Adios Amigos" (Arcade Mode) to unlock Hector Babasco and Lean Molly.
Unlock Characters in Story Mode
Beat the levels shown below on Medium difficulty to unlock the corresponding characters:
2280 Return to Planet X: Ozor Mox
2019 NeoTokyo: Sadako
1853 Wild West: The Colonel
1972 Atom Smasher: Khallos
1920 Aztec Ruins: Stone Golem
Unlock Circus Level
Get a bronze or better in the 'Dam Bursters' challenge in Challenge Mode.
Unlock Cropolite Character
Get a silver or better in the 'Hit Me Baby One Morgue Time' challenge in Challenge Mode.
Unlock Feeder Zombie Character
Get a silver or better in the 'Day Of The Damned' challenge in Challenge Mode.
Unlock Hunchback Character
Get a silver or better in the 'Stain Removal' challenge in Challenge Mode.
Unlock Insect Mutant Character
Get a silver or better in the 'Simian Shooter' challenge in Challenge Mode.
Unlock Lola Varuska
Get a gold or better in the 'Monkey Mayhem' challenge in Challenge Mode.
Unlock Marco The Snitch Character
Get a silver or better in the 'Fallout' challenge in Challenge Mode.
Unlock Mischief Character
Get a silver or better in the 'Monkey Mayhem' challenge in Challenge Mode.
Unlock Pirate Character
Get a gold or better in the 'Trouble At The Docks' challenge in Challenge Mode.
Unlock Private Coal Character
Get a silver or better in the 'Gone Bananas' challenge in Challenge Mode.
Unlock Private Poorly Character
Get a silver or better in the 'Monkey Business' challenge in Challenge Mode.
Unlock Robofish Character
Get a silver or better in the 'Dam Bursters' challenge in Challenge Mode.
Unlock R-One-Oh-Seven Character
Get a silver or better in the 'Where Do The Batteries Go?' challenge in Challenge Mode.
Unlock Rotating Heads Cheat
Beat "Pane in the Neck" in Silver (Challenge Mode).
Unlock Sergio Character
Get a silver or better in the 'Sergio's Last Stand' challenge in Challenge Mode.
Unlock Sewer Zombie Character
Get a silver or better in the 'Fight Off The Living Dead' challenge in Challenge Mode.
Unlock Sgt Rock Character
Get a silver or better in the 'Pick yer Piece' challenge in Challenge Mode.
Unlock Streets Arcade Level
Beat the game on Easy difficulty.
Unlock Viking Character
Get a gold or better in the 'Silent, But Deadly' challenge in Challenge Mode.
Unlock Wood Golem Character
Get a silver or better in the 'Playing With Fire' challenge in Challenge Mode.