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.
The Steam download version of the game is listed as Windows 2000/XP/Vista platform because the executables are modified to use a DOSBox variant (v 0.70); additionally the traditional setup.exe is missing.
It is confirmed that neither Valve or id Software contacted the DOSBox project staff and initially the game didn't includes the TXT´s that must be present under the GPL license (so they failed to fulfill 2 points of the GPL license).
Two days after the launch, there was an update that includes COPYING, AUTHORS and THANKS.txt of the DOSBox 0.7
Many people were angry about Id's decision to include Evilution in Final DOOM - it was originally going to be released as a freeware expansion onto DOOM II.
On April 30, 1997, Final Doom was put on the infamous German index by the BPjS. More information about this topic can be found in the game group.