This is my favourite FPS of all time next to Heretic - Shadow of The Serpent Riders, DooM 2 is a multi-layered FPS game which is the purest example of how the genre should be, fast paced, challenging and meticulously well designed. The levels in DooM 2 are absolute masterpieces, each their own puzzle and often require good navigational skills as some are extremely elaborate and focus on non-linearity and good resource management.
As like the original DooM, the visuals in this are a work of art, each and every texture feels in place, the concept couldn't get much better, the atmosphere is evil and consistent and the architecture is flawless. DooM 2's gameplay is incredibly fast-paced and requires you to maneuver skillfully through hordes of monsters and causing 'in-fighting' between monsters to conserve ammunition.
Each and every slight detail of design this game has was put into consideration; monster placement, switches, the way you progress, keys scattered around the map, secrets, traps, FPS has only come downhill from here, regardless of all the flashy cutscenes and graphics presented in todays games this offers a far deeper experience than pretty much every FPS to date.
DooM 2 is the definitive FPS experience showing how great gameplay and level design work hand in hand with each other and how important that combination is in creating a flawless masterpiece, this is one game I complete atleast 3 times a year from start to finish and have more fun in it with each playthrough, I recommend you play this on Ultra-Violence as that is the way its meant to be played and without saving throughout the levels as that takes away a lot of the challenege.