The GOD of gaming
For a tenner this is the best bargain in history (you can probably get it for less now) I aswell as many other people grew up on this game, without this i would not love games like i do.
The amount of guns there are is amazing, the levels are intellegently built and challenging and there is the BFG 9000, the greatest gun in gaming history and the little face at the bottom of the screen which has become the face of the game, there are countless different monsters raging from the zombie to the cyberdaemon.
Wether you love doom or not, nobody can deny that it defined the FPS genre.
(Goes to worship Doom)