Quake 4 Easter Egg - Hidden Ammo Room

First, get the to Nexus Core level. Next, soon after leaving the start area, proceed into the next room as normal. Next, the door they want you to go through closes and you fight the creatures that ambush you. After the fight is over, save the game.

Now, remember that door that closed right before the fight started? Head back over there. Now, switch to your Blaster and press Ctrl-Alt-~ (the last is the button to the left of the "1" key on the keyboard) to bring up the Console. Type the following without the quotation marks "noclip". This will allow you to pass through walls. Head through the locked door, and around the bend going through the wall at the end of the corridor. After you go through the wall turn around until you see a strange unconnected room. You should see some ammo like for your Dark Matter Gun, and an armor vest. Head over to the room. This "room" contains all the guns, ammo, and upgrades you get during the course of the game. If you want to cheat and stock up, bring up the console again and type noclip to turn noclipping off. After done here, head through the wall the vest is/was located and you should see some grey-conduits surrounded by blue (I appologize if this is a little vague). When you pass through this wall, you should be back where you started. Turn noclipping off, and continue as normal.