Essentially all of the classic Sierra and Lucasarts libraries. The Quest games are wonderful and I'd love to have a new version that worked.
I'd like to see Relentless and its sequel (I never got the sequel, so I'm just hoping it was good based on the first one). I think they were both called Little Big Adventure. The first was awesome.
Planescape, Arcanum, Bloodliens, and ToEE. The Ultimas. I never got around to Might and Magic or Wizardry, but I'd give them a try i they were here, as I understand they were very good. Darklands. I had the original, and my computer ran out of RAM in robber knight castles. I have played various DOSbox versions over the years and none of them have let me complete the damn game. I want Darklands!
Serf City (In US. I think Settlers I in the rest of the world) and Settlers II.
Sid Meier's Alpha Centauri. Sim City 2000.
I'd probably play the Wing Commander games. Especially if they come in a pack.
Syndicate I and II. X-Com and X-Com 2. That first game is still the most perfect thing I've ever played.