Press / to display the talk window, then enter one of the following codes to activate the corresponding cheat function. 

code and press enter: 

God mode -- iamgod 

Full health -- smoghead 

Enable debug mode -- debug on 

Disable debug mode -- debug off 

God mode in last stage -- iamgoddess 

Kill nearby enemies -- giants 

Land with flight mode -- active drop 

List weapon names in debug mode -- all weapons 

Obtain indicated item -- gimme **** 

Remove fog -- foghack 

Switch view to nearest enemy -- switch 

Toggle flight mode -- enabled fly 

Unlock doors -- opensezme 

 

Developer mode: 

Hold [Shift] while starting the game. Click on the "Developer Mode" tab to access the developer options. 

 

Extra money: 

Get items repaired before selling them. The difference in the cost of repair and money given when the item is sold is often in your favor.