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

Code - Effect

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)