Final DOOM (itch)
Final DOOM is the last id Tech 1 DOOM game. It adds two separate 32 level episodes: TNT: Evilution and The Plutonia Experiment to DOOM II.
Gameplay in both episodes is completely identical to DOOM II, right down to the level progression (i.e. 30 levels and two secret levels), although they have a new backstory (both following directly on DOOM II rather than each other. Other changes are some new textures and, in TNT's case a few new music tracks.
Neither episode was made by id Software, but rather by two groups of individuals hired by them; Team TNT and the Casali brothers.
Two New, 32-Level DOOM II Episodes.
Far from earth, the UAC recommenced their experiments on on of the moons of Jupiter. A spaceship, mistaken for a supply vexxel on radar, hovered above the base. Hideous demons poured out, blanketing the base with death. All your comrades were quickly slaughtered or zombified. This time, it's not about survival. It's about revenge.
The Plutonia Experiment:
Every effort has been made by the nation's top scientists to close the seven interdimensional Gates of Hell, but one portal remains open. Alone, you must infiltrate the ravaged complex, defeat the demon Gatekeeper and seal the last Hell-hole before the undead are prepared to, once again, take over the world.