Press ` to open the command screen and enter one of the following codes:
AceEvans - Be Invisible
StanGable - Infinite weapons
RogerPhilips - Laser Targets Avaible
JeffersonDarcy - Either you get to be Invincible or get extra health.
Press "~" key to access console prompt and type in "coolnvg", Hit "Enter".
This gives you a different and more gradient Night Vision view that I find easier to see. Works when you use the scope ,too.