There are quite a few games in the series. If you're wanting to play them all in order, here's a list.(Game titles are variants of the same game.)
- Doom: Evil Unleashed, The Ultimate Doom, Doom
- Doom II: Hell on Earth, Doom II
- Final Doom(TNT Evilution, Plutonia Experiment)
- Doom 64
- Doom 3, Doom 3: Resurrection of Evil(expansion pack), Doom 3 BFG Edition
- Doom RPG
- Doom II RPG