Doom, the originator of the First Person Shooter (FPS). I remember spending hours playing this in 1994. While playing Doom again I remember, the suspense of wondering what was waiting for me around a corner and blasting the heck out of it. Apart from shooting the enemies, there is the added challenge of solving the maze that you find yourself in. For an added competition facture, you can improve on your time on each level. I somehow remembering the graphics being more realistic, it must be the alternative reality that Doom created in my mind
FPS is definitely my favourite genre of games. I really got hooked with this particular genre of games when the original Medal of Honor came out. These games told the story of WWII and put the player in the middle of such events as D-Day. They also added a component of online playing where you could battle against friends by hosting a match on your own computer or a dedicated server. This series of games lead my love of another story line which was Call of Duty, a FPS in a more modern setting.