Cheat Codes
While playing, press ~ (tilde) to bring up the console, then type any of the following cheat codes: 

Code                      Result: 
Invulnerability 1         God Mode (0=Disable) 
Daytime #                 Set Daytime to # (1-24) 
Debug 1                   Debug Mode (0=Disable) 
DayTimespeed #            Set Daytime Speed to # 
CreateUnit #              Create Unit # (#=Name)
Create Unit Cheat
On the CreateUnit # cheat code, you can type a single letter to get a listing of all possible creations for that letter.
Example: CreateUnit C will show all units starting with C.