Doom 2 has to be my favourite first person shooter ever. I love pretty much everything that ID software has come out with, but Doom 2 has to be one of the ones I've had the most fun with as far as single player fun goes. Another one that was pretty humourous to play was Castle Wolfenstien and Spear of Destiny. Both of them are pretty wicked games. I love them all. UT99 or Unreal Tournament : GOTY(Game of the year) are a little newer, and I found it to be really fun as well. I liked the simpler map editor to be the most fun. I spent more time creating my own maps, than actually playing the game. Some more classic ones are Blake Stone, Duke Nukem 3D, and Shadow Warrior. How about yourself? Which of the older PC FPS's do you remember playing? Or still play for that matter. Any obscure ones that you don't think people know about?