Does 2000 count as retro yet?
Deus Ex, the other games are all simplified and streamlined, missing lots of depth in gameplay and replayability. Not that I hate the other games but try 5+ playthroughs and you'll feel the difference. Also the original had the best story and dialog.
And the original is an insane modding platform (just check out !deus_ex_randomizer@lemmy.mods4ever.com lol), and the other games don't have any modding tools at all.
Also RollerCoaster Tycoon 1&2, especially with OpenRCT2