Diablo. The atmosphere of this game is second to none. My favorite action RPG. Every quest means something. Every unit killed mattered. Every new level actually felt like a step closer.
I know that this year had a lot of popular releases. But for me the first Diablo is so much better than all of them that I do not even want to mention any one of them. For me Diablo is just that much better than any other game this year. I would in a heartbeat trash all of them just to be able to keep playing Diablo. And that includes a lot of games I really like some even the best installments in their series. But they simply pale in the shadow of of Diablo.

That's a tough one. I might have to give it to Star Fox 64. Such a fun game with tons of replay value. I sunk so many hours into that game back in the late 90s. Final Fantasy VII would be a very close second, though.

I would have given the #1 spot to Mario Kart 64 since it released in NA in 1997, but since it was released in Japan in 1996, it doesn't qualify for purposes of this thread.

For me it is the original Carmageddon on PC, it has unmatched car physics.

In hindsight FF7. At the time Goldeneye. Hindsight always wins of course.

N64 aged poorly in many regards. Goldeneye is so hard to play today. The controls and framerate are awful. Granted emulation helps with remapping.