Doom

View credits:
Reset the game three times.

Hint: Real first episode completion:
You may have noticed that sometimes when you complete the first episode, the game returns to the title screen. You cannot continue to the second episode from the first episode if you are playing at the two least difficult settings.

Hint: Inferno: Easier difficulty:
To make the "Inferno" chapter easier, complete the "Shores of Hell" on the "Hurt Me Plenty" difficulty setting. You will start the "Inferno" chapter on "Hurt Me Plenty" instead of "Ultra Violence" or "Nightmare" settings.

Hint: Enemies:

Former Soldiers: They resemble your old friends, but now they just fire pistols at you. They drop clips for the chaingun and pistol when killed.
Former Sergeants: Meaner and tougher. They carry shotguns and do more damage then soldiers. They drop shotguns when killed.
Imp: This creature throws fireballs and takes more bullets to kill.
Demon: Appear in most areas and can rip your head off if you are not careful. If you see more of them, use the chaingun.
Cacodemon: These creatures are ugly and have one big mouth. If they see you, they will fire lightning balls from their mouth. Use your rockets.
Mancubus: You have to use more then a chaingun to kill them. Use ammo with caution.
Arachnotron: Fires plasma energy at you. Use your rifle.
Spider Demon: The ultimate enemy. Has a super chaingun mounted on her body. Use your plasma rifle or rocket launcher.