I have added an interface to input cheats, and of course the backend of this. Current cheats include:

unlimited health
unlimited time
faster movement
no need to use keys (i have a door/key system)
triple firing lasers (normally there is only one)
grenades (changes your weapon to grenades)

But the question is, how will i tell the user the cheat codes? Normally cheats would be sold by the programmer, but this isn't that sort of game currently!