During gameplay press ENTER to display the 
communication window, then enter the code.


Result - Code  

Fart when walking - silentbutdeadly 
2D players - turnpunchkick 
Disable AI - nobrainer 
Wounding shots - kill wounddeath 
Very heavy breathing - 1-900 
Selected character is invincible - avatargod 
Invisible mode - theshadowknows 
Refill ammunition - 5fingerdiscount 
Toggle victory conditions - explore 
Monocle mode - monocle 
Clodhopper mode - clodhopper 
Big head - bignoggin 
Mega head - meganoggin 
Stumpy mode - stumpy 
Debug keys (activate) - debugkeys 
Do suicide - death
Team invincible - teamgod 
Team invisible - teamshadow