Successfully complete story mode on the easy difficulty setting to unlock a "View Credits" option on the main character selection screen.

Successfully complete the 1935 Tomb level in story mode on the easy difficulty setting to unlock Cultist as a playable character in arcade mode. Completed the level in under 1 minute to also unlock the Paintball mode cheat. Complete the level on the normal difficulty setting to unlock the Graveyard level in arcade mode. Complete the level on the hard difficulty setting to unlock Eyes Mummy as a playable character in arcade mode.

Successfully complete the 1970 Chinese level in story mode on the easy difficulty setting to unlock Chinese Chef as a playable character in arcade mode. Complete the level on the normal difficulty setting to unlock the Site level in arcade mode. Complete the level on the hard difficulty setting to unlock Suit Hoodlum as a playable character in arcade mode.

Successfully complete the 2005 Cyberden level in story mode on the easy difficulty setting to unlock the 1950 Village, 1985 Chemical Plant, and 2020 Planet X levels in story mode; Dr Seth Graven. Dr Kate Nadir, Fingers McKenzie, Ravelle Velvet, Sebastian Photon, Angel Perez, and Badass Cyborg as playable characters in arcade mode; and Badass Cyborg, Siamese Cyborg, and Female Cyborg as Bots in arcade mode. Complete the level on the normal difficulty setting to unlock the Streets level in arcade mode.

Successfully complete the 1950 Village level in story mode on the easy difficulty setting to unlock the 1950 Village level in arcade mode; and "Period Horror" as a Bot Set in arcade mode. Complete the level on the normal difficulty setting to unlock the Castle level in arcade mode.

Successfully complete the 1985 Chemical Plant level in story mode on the easy difficulty setting to unlock the 1985 Chemical Plant level in arcade mode; "Usual Suspects" as a Bot Set in arcade mode; and Lumberjack, Malehood, and Waiter as Bots in arcade mode. Complete the level on the normal difficulty setting to unlock the Bank level in arcade mode.

Successfully complete the 2020 Planet X level in story mode on the easy difficulty setting to unlock the 1965 Mansion, 2000 Docks, and 2035 Spaceways levels in story mode; 2020 Planet X level in arcade mode; Peekabo Jones, Mary-Beth Casey, Jacques Misere, Olga Strom, R108, and Gretel as playable characters in arcade mode; "Space Opera" as a Bot Set in arcade mode; and Tuxedo Cyborg, Red Alien, and Green Alien as Bots in arcade mode. Complete the level on the normal difficulty setting to unlock the Spaceship level in arcade mode.

Successfully complete the 1965 Mansion level in story mode on the easy difficulty setting to unlock the 1965 Mansion level in arcade mode; "Horror Shocker" as a Bot Set in arcade mode; and Fishwife Mutant, Hick Hyde, Insect Mutant, Overall Mutant, Police Zombie, Girl Zombie, Skull Zombie, and Jacket Zombie as Bots in arcade mode. Note: Set "Auto Aim" to toggle, leave it on, and crouch to get easier head shots to complete this level easier. Complete the level on the normal difficulty setting to unlock the Mall level in arcade mode.

Successfully complete the 2000 Docks level in story mode on the easy difficulty setting to unlock the 2000 Docks level in arcade mode; "Law and Order" as a Bot Set in arcade mode; and Male Soldier, Female Soldier, Gasmask Soldier, Male SWAT, Female SWAT, and Gasmask SWAT as Bots in arcade mode. Note: There are a lot of snipers in high perches by the waterfront, so be alert in this level. Complete the level on the normal difficulty setting to unlock the Compound level in arcade mode.

Successfully complete the 2035 Spaceways level in story mode on the easy difficulty setting to unlock the 2035 Spaceways level and "Space Opera" as a Bot Set in arcade mode. Complete the level on the normal difficulty setting to unlock the Warzone level in arcade mode.

Successfully complete story mode to unlock challenge mode, which allows you to compete in different challenging situations.

Successfully complete all challenges to unlock "The Living Dead" as a Bot Set in arcade mode and the Challenge 1-B Putrid Punchout level.

Successfully complete all challenges to unlock Green Zombie and Brown Zombie as playable characters in arcade mode and the Challenge 1-C Dusk Of The Dead level.

Successfully complete all challenges to unlock Police Zombie, Skull Zombie, and Jacket Zombie as playable characters in arcade mode and the Challenge 2-A Flock Around The Dock level.

Successfully complete all challenges to unlock Duckman Drake as a Bot in arcade mode and the Challenge 2-B Pro Am Duck Shoot level.

Successfully complete all challenges to unlock the "All Enemies Are Ducks" cheat and the Challenge 2-C Crispy Duck level.

Successfully complete all challenges to unlock Duckman Drake as a playable character in arcade mode and the Challenge 3-A Tin Man level.

Successfully complete all challenges to unlock Robofish as Bot in arcade mode and the Challenge 3-B Lobster Run level.

Successfully complete all challenges to unlock the "All Enemies Are Robofish" cheat and the Challenge 3-C Bowl Them Over level.

Successfully complete all challenges to unlock Robofish as a playable character in arcade mode and the Challenge 4-A Shame If Something Got Broken level.

Successfully complete all challenges to unlock the Challenge 4-B Don't Wait Around level.

Successfully complete all challenges to unlock the "Enemy Bricks" cheat and the Challenge 4-C Brick Flung High level.

Successfully complete all challenges to unlock the brick as a weapon in arcade mode and the Challenge 5-A First Impressions level.

Successfully complete all challenges to unlock The Impersonator as Bot in arcade mode and the Challenge 5-B Lasting Impressions level.

Successfully complete all challenges to unlock the "All Enemies Are Impersonators" cheat and the Challenge 5-C Who's he Trying to Impress? level.

Successfully complete all challenges to unlock The Impersonator as a playable character in arcade mode and the Challenge 6-A Barrel Blast level.

Successfully complete all challenges to unlock the Challenge 6-B Bodyguard level.

Successfully complete all challenges to unlock Gasmask SWAT as playable character in arcade mode and the Challenge 6-C Heist level.

Successfully complete all challenges to unlock Veiled SWAT as a Bot and playable character in arcade mode and the Challenge 7-A Shop 'Til You Drop level.

Successfully complete all challenges to unlock Ginger as a Bot in arcade mode and the Challenge 7-B Sorry, Was That Your Bag? level.

Successfully complete all challenges to unlock "All Enemies Are Gingerbreads" cheat and the Challenge 7-C Everyone Must Go! level.

Successfully complete all challenges to unlock Gingerbead as a playable character in arcade mode and the Challenge 8-A Girls 'n' Boys level.

Successfully complete all challenges to unlock Fun-Bunny as a Bot in arcade mode and the Challenge 8-B Dinner Dates level.

Successfully complete all challenges to unlock the "All Enemies Are Bunnies" cheat and the Challenge 8-C Bone Grab level.

Successfully complete all challenges to unlock Farrah Fun-Bunny as a playable character in arcade mode and the Challenge 9-A I Can't Hear Anyone Screaming level.

Successfully complete all challenges to unlock TimeSplitters as a Bot Set in arcade mode; TimeSplitter, and TimeSplitter (Same name, different character) as bots in arcade mode; and the Challenge 9-B Flight Delay level.

Successfully complete all challenges to unlock TimeSplitter as a playable character in arcade mode.