And believe it or not, the game wasn't even developed by idSoftware.
Is it some sort of expansion pack or a level pack for the second game? Well, the answer is surprisingly a "NO", because TNT Evilution is an FPS that uses elements from Doom 2, like weapons, NPCs and so on. After Doom came Doom 2, which my personal favorite retro horror first person shooter, but what about Doom 2: TNT Evilution. Normally, it cannot compete with the newer horror games like Dead Space.
Who can deny the fact that Doom is the ultimate old-school horror FPS out there.