Successfully complete the first three levels in story mode on any difficulty setting to unlock the Village, Chemical Plant, and Planet-X levels in arcade mode. Additionally, Dr. Seth Graven, Dr. Katje Nadir, Fingers McKenzie, Ravelle Velvet, Sebastian Photon, and Angel Perez Bots will also be unlocked as playable characters in arcade mode.
Cultist
Successfully complete the 1935 Tomb level in story mode on the easy difficulty setting to unlock Cultist in arcade mode.
Chinese Chef
Successfully complete the 1970 Chinese level in story mode on the easy difficulty setting to unlock Chinese Chef in arcade mode.
Badass Cyborg
Successfully complete the 2005 Cyberden level in story mode on the easy difficulty setting to unlock Badass Cyborg in arcade mode.
1950 Village level reward
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.
1985 Chemical Plant level reward
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.
2020 Planet X level reward
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.
1965 Mansion level reward
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.
2000 Docks level reward
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.
2035 Spaceways level reward
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.
Challenge mode
Successfully complete story mode to unlock challenge mode, which allows you to compete in different challenging situations.
Challenge 3A Tin Man level reward
Successfully complete all challenges to unlock the Challenge 3B Lobster Run level and Robofish as a Bot in arcade mode.
Challenge 3B Lobster Run level reward
Successfully complete all challenges to unlock the Challenge 3C Bowl Them Over level and the "All Enemies Are Robofish" cheat.
Challenge 3C Bowl Them Over level reward
Successfully complete all challenges to unlock Robofish as a playable character in arcade mode.
Challenge 4A Shame if Something Got Broken level reward
Successfully complete all challenges to unlock the Challenge 4B Don't Wait Around level.
Challenge 4B Don't Wait Around level reward
Successfully complete all challenges to unlock the Challenge 4C Brick Flung High level and the "Enemy Bricks" cheat.
Challenge 4C Brick Flung High level reward
Successfully complete all challenges to unlock the brick as a weapon in arcade mode.
Extra characters
Complete the following levels in each difficulty setting in the following time limit to open up extra options:
Tomb:
Easy - 1 minute - Paintball Mode
Norm - 3m 10s - Priestess Character
Hard - 6m - Teeth Mummy Character
Chinese:
Easy - 1m 15s - Chinese Waiter Character
Norm - 3m - Weird Gun Sounds Mode
Hard - 6m - Mr Big Character
Cyberden:
Easy - 50s - Siamese Cyborg Character
Norm - 1m 30s - Tuxedo Cyborg Character
Hard - 3m - Enemy Rockets Mode
Village:
Easy - 30s - All Heads Detachable Mode
Norm - 1m 30s - Hick Hyde Character
Hard - 4m - Insect Mutant Character
Chemical Plant:
Easy - 30s - Male/Female SWAT Characters
Norm - 1m 10s - Infinte Ammo Mode
Hard - 6m - Malehood Character
Planet X:
Easy - 55s - Green Alien Character
Norm - 1m 30s - Float Alien Character
Hard - 3m - No Heads Mode
Mansion:
Easy - 1m 45s - Big Head Mode
Norm - 5m - ?
Hard - 10m - Girl Zombie Character
Docks:
Easy - 1m 15s - Male/Female Soldier Charaters
Norm - 1m 30s - Big Hands Mode
Hard - 2m - Shock Trooper Character
Spaceways:
Easy - 1m 10s - Red Alien Character
Norm - 1m 20s - Female Alien Character
Hard - 2m - Small Heads Mode
How to get overall mutant
To unlock overall Mutant you must beat the Mansion level in under 5 minutes.