this thread is making me feel like an old twat, rather than just a twat.
Don't worry, you're a relatively young twat, all things considered. :-)
The first game I thought "Wow, it's like I'm really there!" Was
Jet! running on an 8086, and again when I ran it on an 80286 possibly with the math-coprocessor -- better framerate but suddenly unbeatable enemies. But that was after high school.
The other game which really wowed me was an Apple ][ game (well, an Apple //e game) which took place entirely on the surface of a vast ocean. I remember it played in hi-res or "double hi-res" and felt incredibly fluid. Wikipedia's list of Apple games is not showing it. The Jordan Mechner games
Karateka and
Prince of Persia's mocapped animation also blew my mind.