In no particular order, I've also not included some obvious ones like Doom as they go without saying, just so I could include more.
Alone in the Dark Trilogy (1992, 1993, 1994). I know technically this collection was published after 1997 but I couldn't decide which one to choose so this'll do.
BioForge (1995). Absolutely legendary game. Beating a naked blue cyborg murderer to death with his own arm in the first 10 minutes was a memorable opener.
Wing Commander: Privateer (1993). Amazing feeling of freedom as you explored space, battled pirates, visited beautiful 3D rendered space ports, trading, upgraded your ship... better than No Man's Sky.
X-Wing (1993). Back when Star Wars was legendary, this was an incredible video game dream come to life.
Daggerfall (1996). Lots and lots of game to keep me busy. I only ever played this on other people's PC's at the time and always did so with huge amounts of envy.
Syndicate (1993). Brilliant stylish game that mostly involved arming your agents with Gauss guns and flamethrowers and creating complete chaos.
Gabriel Knight: The Beast Within (1995). The only FMV era game that truly superceded its gimmick in being a superb game. Brilliant story, evocative locations, music, good acting (with even the loss of Tim Curry as Gabriel not being too much of a downer). Also absolutely love first game.
Fallout (1997). If I'm honest I prefer Fallout 2, played that first and played it more, but as I'm restricted to pre-98 games it will have to be my post apocalyptic rpg fix.
Monkey Island 2: Le Chuck's Revenge (1991). This was a showcase of a title back in the day, with some of the best art and animation seen in a game up until then.
UFO: Enemy Unknown (1994). Such a wonderful, deep game that offered an unparalleled strategy experience. Nothing matched renaming all your soldiers to your friends, family and girls you fancied only to watch them all get wiped out during an alien terror attack.
This is horrible. There are too many games others have included that I would easily add here: Doom, Doom 2, Strife, Sim City 2000, Lemmings 3D, Blade Runner, Carmaggedon 2, Duke Nukem 3D, Dark Forces, Rise of the Triad, Quarantine, Hand of Fate, Ultima Underworld 1 and 2.... I could go on. it's criminal not to be able to include them. What a gaming era.