Perhaps this thread might be useful beyond my own personal wants. In any case, I've recently got a 486 build working, complete with an OPL3 card and a Stealth 24 VLB card. I come to you because... I've done sweet fuck all with it. I was gonna play Doom, but that's too much for a DX2-66 to play comfortably- and I can't get stereo sound.
So instead, I'll work backwards. This period, pre-1993, is way to early for me to have knowledge of. Most games I see come up are kinda basic little time wasters, I come to ask for narrative or immersive games, the more and deeper the story the better.
Doom is a bit chuggy on a 486, but recently I started playing it again to give myself a break from a long RPG I'm in the middle of, and I'm actually getting used to the chugginess to the point where the framerate seems not so bad. And I've got my 486 clocked at 40Mhz too.
As for recommendations, here's some from different genres that IMO are highly narrative and/or immersive. I've completed many of them, so can attest to their quality.
Flight Sims with campaign:
*Aces of the Pacific
Aces over Europe
*Day of the Tentacle
*Indiana Jones and the Fate of Atlantis
*Quest for Glory I, II, III
*Space Quest IV, V
*The Secret of Monkey Island
*(and other Lucas Arts and Sierra titles)
*Alone in the Dark
*Betrayal at Krondor
Lands of Lore
*Might and Magic: World of Xeen
Ravenloft I, II
Ultima Underworld I, II
*Ultima VII Pt 1
Ultima VII Pt 2
*Worlds of Ultima: Martian Dreams
*Worlds of Ultima: Savage Empire
Space Shooter with story-driven campaign:
*Wing Commander I
Wing Commander II
*slow these games down by de-turboing or disabling L1 cache. They will run too fast on a 486DX2/66