If you miss the good ol' style of play from games like Doom or Quake, you should definately consider Half-Life. You've probably heard that over a million times, so I guess I'm just being redundant. Other good alternatives to the wave of death-match based games are Deus Ex, System Shock 2, the original Unreal, Thief 1 & 2, and maybe even the expansion set for HL, Opposing Force. They all concentrate completely on a good solid single player experience and two of them don't even have multi-player support. Anyway, pick up a copy of these games and tell me how ya like em.