In this insanely popular first person shooter, the player, as a lone Marine, must clear out levels by avoiding and/or killing various creatures while keeping an eye on his armor, health, and ammo. Certain switches and buttons also need to be utilized in order to progress through the game.
If you have a six button controller, press pause during a game, then press Up/Mode/A/C for all weapons and keys
To quickly switch to the BFG, if you have a six button controller, hold down the Mode button and press Z.