Waaay harder to answer than the 2006 one...
Final Fantasy Tactics is probably the one I played the most. Half-Life is super obvious, but what's less obvious is the impact that game had on online gaming. Quake was still very popular online, but CS and TFC were massive (though those were 1999).
Xenogears, Ocarina of Time, Gran Turismo, Metal Gear Solid, Grim Fandango, Fallout 2, Starcraft, MARIO PARTY(!!), Baldur's Gate, Thief... damn, that was a good year.