Doom 64

On any skill level, beat Level 32: Hectic using the exit where you need each key. Then, for the rest of the game, there will be a Features menu when you press Pause (it will disappear if you shut off your Nintendo 64 or you exit the game).

To unlock Hectic, you need to go to the first level, and shoot EVERY explosive barrel in the level, EXCEPT for the first one you see when on the staging platform. After you shoot the other 9 barrels, use the teleporter (Hidden in one of the walls in the main corridor) to return to the start of the level. Then, shoot the barrel you left and turn directly behind you, and go into the room with the berzerk pack. There will be an open teleporter- a blood stain marks the entrance. Be sure to hurry- it doesn't stay open long!

Once you get here, good luck- some consider this one of the hardest Doom levels ever made! Once you beat this level, you unlock the Features menu.

On the Title Screen, click on the Options and from the Options, choose Password and then enter these codes:

At the password prompt, enter this password. Then, return to the title screen and wait for the game's introduction screen to show (just wait for about 30 seconds, and the screen will change). Now wait for the 3 demos. After the 3rd demo, there will be a 4th demo, showing how to beat Level 32: Hectic.

When you are on the Playground Level, the key to dodging the bullets from Arachnitrons, is simply to not stop moving. Simply keep running and you will not be hit. As for the Cyberdemon that emerges after you defeat the Arachnitrons, simply keep your distance from it and fire at it. When it returns fire, simply run behind one of the four large pillars and you should be safe. As for the Mancubis’ that com afterwards, they will be easy to kill. Pick them off one at a time. By the time that only two remain, you will be fine.

It is, however, important to try to not grab the Partial Invisibility items as they make enemy fire unpredictable and hence, harder to dodge. After defeating the Arachnitrons, you should grab every box of Rockets and wait until you become visible again before you grab the Megasphere.

Enter these at the password screen to skip to that level.

Go to the Password screen and enter the following:

You can exploit the N64 controller's "Neutral position reset"; feature easily in this game. What you do is hold down on the control stick, then simultaneously press L+R+Start. What this does is set the "down" position on the joystick to neutral. So what happens when you press up? You go REALLY FAST! Problem with this is that the neutral position is now "Down." To fix it, just let the joystick go neutral, then press the button combination again.

This works GREAT in the first hidden level, "Outpost Omega" when trying to do the switch puzzle to get the artifact.

Enter W93M 7H2O BCYO PSVB. This code will give you 100 health, 200 armour, all weapons, full ammo and a backpack. It'll also supply you with the three pentagram icons that make your laser three times stronger than the BFG and can kill bosses in four seconds flat. These useful pentagrams also let you use the three mysterious switches in the last level, closing the gates which spawn the monsters.