Heroes of Might and Magic II, I still will fire it up to play occasionally! I have so many fond memories of me and my dad playing into the long hours of the night.
Gaming
I didn't play it on DOS, though it also saw a DOS release, but Syndicate would be high on my list.
Carmageddon was a late DOS release that I liked.
I never did actually get around to The Ancient Art of War, though I did want to play that.
I didn't play it on DOS, though it saw a DOS release, but the original Sim City aged pretty well.
Theme Park. So classic.
Ultima Underworld. Bought my first sound card for this game.
Duke Nukem II. Also love the first one. Apogee in general made some really excellent DOS games.
Probably Lotus Racing (ran off one floppy), then Quake 1 and Carmageddon 1. Never really gamed much after those few.
I got into ZZT, a "topdown" 2d game with its own map editor and even a rudimentary scripting language. Stumbled on it because I wanted to make games. People made some seriously impressive shit on that thing and its successors.
Going by most influential, it'd have to either be Doom or Ultima Underworld. Both of these inspired entire genre's that still live on to this day (FPS and First-Person RPG's like The Elder Scrolls). Personally? Ultima 7.
Supaplex and Gorillas are my go tos!
Probably X-Com: UFO Defense. Got really into it and holy hell got angry at that game. But damn it made me want to play more!
I never had a DOS computer back then and only played a few games through emulators in recent years. It has to be DOOM for me.
Sid Meier's covert action. Absolutely amazing spy game with lots of minigames and a randomly generated hierarchy of bad guys to catch every mission. Really want a remaster but I don't think I'm getting one.
Every once on a while i get back to Mad TV. Casual game before it was cool. Also Indiana Jones: Fate of Atlantis
Wolfenstein 3D, my first ever PC game
my dad gave me a floppy disk from one of his coworkers with instructions on how to navigate and run the game from DOS and I felt like a hacker lol
Crusader: No Remorse/No Regret
Sometimes I wish they made an FPS reboot, then I remember EA owns it.
Hard to say. Secret Agent, Treasure Mountain, Azrael's Tear, Chill Manor, etc. All solid games. Hard to pick just one.
Star Command was my favorite. Loved recruiting crew members, buying and upgrading ships, and going around the galaxy to complete missions. It's the game that got me hooked on RPGs as a kid
Space Hulk would definitely be mine
Gunship 2000. Shit was amazing.
Ultima series.
Star Control II for sure. Fantastic game, still one of the best story-based games I've played. Heavily inspired a lot of more modern franchises, too, including Mass Effect.
Doom, Duke Nukem 3d, Zak McKraken and the alien mindbenders, One Must Fall 2097