Unlimited Kaos mode time:
Finish every Kaos level in arcade mode.

Chinatown level:
By scoring 25,000 points in the Capitol City Mall level in Kaos mode.

East Side level:
By scoring 50,000 points in the Chinatown level in Kaos mode.

Corporation Central level:
By scoring 100,000 points in the East Side level in Kaos mode.

Last Clone Standing levels:
Finish the three minute and five minute versions of a level to unlock the Last Clone Standing version of that map in Kaos mode.

Recover from burning:
When on fire, enable any weapon code to get up.

Use head as a weapon:
Use a shotgun and shoot them. A part of their body will fall off and you can pick it up.

Disable bombers:
To disable bombers, set them on fire with the flamethrower. They will die without exploding.