FOR PC PLAYERS:
1. Start a new game - select single player and Scourge of Armagon
2. Now hit the ~ key and enter this "map hip1m4"
3. Enter "god" and "noclip"
4. You are looking for teleporting at the bottom of the level. It is nearly in front of your starting location, pretty much head down and forward and you should find it quickly. Go into the tiny room, turn off no clipping and it will teleport you to another portal and that is the true exist (you can probably noclip there but this is faster)
IF GOD MODE ISNT WORKING: (all credit goes to Chocotoaco119)
According to a recent post on reddit you need to type "sv_cheats 1" hit enter and then type "god". You should get a notif in the console that god mode is on.
MAKE SURE YOU TYPE "sv_cheats 0" AFTER YOU HAVE ACTIVATED GOD MODE OTHERWISE YOU WILL NULL THE ACHIEVEMENT. God mode will still stay active after entering