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!
Gaming
Doom, Duke Nukem 3d, Zak McKraken and the alien mindbenders, One Must Fall 2097
Carmageddon
Kings Quest games for sure. IV was the one I played the most, it was a buggy mess, but I loved it.
ZZT was an amazing game where you could make your own games and program "objects" using a simple scripting language. It was my first programming language.
It was Tim Sweeney's first game. I've never played Fortnight.
Bunch of greats mentioned so far. I was a big fan of an older game called “Millenium: Return to earth” in which you colonized the solar system. One of the few games I had that came on the larger, five inch floppies.
Indiana Jones and the Fate of Atlantis Truly a masterpiece or maybe I have rose tinted glasses A real puzzler with a decent amount of replayability
I cannot remember the name but you got to choose between a boy character and a girl character and each stage you had to get all the collectibles to open the door. It was a 2d platformer as well.
Edit: Turns out the game is called Word Rescue.
DOOM
DOOOOM, the first actually good game that i played as a kid. I went from tetris to doom and it was insane haha
was road rash on DOS? played that a lot. wolf 3d too.
Wing Commander Privateer - I love a good economy game in my spaceship game.
Mechwarrior - Battletech 1st person. Get you a 30 foot tall robot and shoot some lasers at other giant robots. Go for the knees.