in options select controls then advance then allow console prees ` (topp left button below escape) and type
to allow cheats then
impulse 101 to give all wepons
Open the developers console by pressing the ` button, and type in "upgrade_portalgun".
This will give you the portal gun and allow the use of the blue and orange portals.
Enable the console and type sv_cheats 1 to enable cheat use. Below is a list of codes you can put on:
Invincible / God:-
type "god" (without the quotation marks) in the console.
Type "impulse 101" (without the quotation marks) in the console.
Noclip / No gravity:-
Type "noclip" (without the quotation marks) in the console.
Buddha / 1 Health:-
(stops you from getting below 1 health) type "buddha".
(allows you to see each models boundaries) type "picker".