I am Zelda fan, so I should be voting for OoT, right? And maybe I would if it was some other year, that is not as stacked with great games. Or if I wasn't Zelda fan that, although considers Zelda as one of TOP 10 gaming franchises, doesn't rate any Zelda above 8.5/10 (which is fine, my most beloved games rarely go to 9/10 or higher). Or if I didn't thought OoT was actual step back from 2D Zeldas in many aspects. Anyway....
It would be easy for me to vote for Fallout 2 - it is one of my all time favourites, and often comes up on top, depending on a year I do the list. It was mechanically improved over Fallout 1, it was more open to how you want to play and it was bigger. Yes, Fallout 1 has better story, and some of the changes to humor in Fallout 2 are not welcome by everyone, but it is still one of the top games in Pantheon of CRPG Greatest. It is by far my favourite game from that year, with Might and Magic VI being second.
Yet I can't not vote for Half-Life. Not only it was fantastic game, but it was blueprint for different breed of FPS games and it changed (for good or worse) how FPS games are made from that point on.
Some other games I really loved from that year are Grim Fandango, Thief: Dark Project, Baldur's Gate, StarCraft and often these days overlooked Commandos: Behind the Enemy Lines - back when it launched it was very much appreciated for doing something quite different with squad based tactical games basing its complete gameplay around stealth and detecting patterns in enemy routines.