Doom

Mother of all First person shooters (ok, wolfenstien was first but it was boring). In this game you are stuck on one of the moons on Mars guarding the geeks that work there and then a experiment goes wrong (like they always do) and the portal to hell opens up and demons attack and rip your friends apart. You need to slay the hordes of hell and stop them. Fun both in single and multiplayer, co-operative rules . Coolest weapon must have been the plasma gun and the chainsaw, I like the idea that they had any use of a chainsaw in space :)

Doom 2: Hell on Earth

You returned to earth at the end of doom and find out that your friends from hell have arrived before you. More monsters that need to die, more levels and also a nice double shotgun for you to use.

Master Levels for Doom II

Expansion pack to Doom 2 with 21 new levels. They are not connected so you start without any weapons beside the pistol on each level.

Final Doom

Two more campaigns for Doom 2, The Plutonia Experiment and TNT: Evilution with 32 levels each. Really difficult and you have to walk around looking for each and every spare bullet you can find.

Doom 3

Doom was action and Doom 3 try to be a horror game. But it does not work as everything is so predictable that one almost fall asleep. Every monsters stands where you think it will and the only horror is when you walk to the next level and see that it is the same sci-fi labs environment as the last one. There are max three monsters at once and the first time you meet a new monster they break the flow with a worthless cut-scene to show it off. Doom I and II are great games and Doom 3 does not deserve to use the same name.

Doom 3: Resurrection of Evil

This is a basic Doom 3 expansion without any real value. All bad things on Doom 3 still apply and they also added a new weapon that works the same as the Gravity Gun in half life 2. There is not much use for it as so few things in Doom 3 can be interacted with.

Doom II: RPG

Turn based first person shooter where you go a UAC base on the Moon to stop the demons from hell.

Doom

So fun. Get it now :).

Doom 64

Takes ideas from both Doom and Doom II and have lots of original content. Fun to play and my only complaint is that levels are a bit small at times.