the easy (and unfortunately boring) answer to this question is commander keen. i'm sorry, it's just the way it has to be. i have a commander keen tattoo on my forearm. playing commander keen: secret of the oracle is one of my earliest memories. i still have a sheet of scrap paper where i translated the standard galactic alphabet and every sign in the game (including that one level in episode one where they spell out FUCK or SHIT or something like that - a thrilling discovery when you're ten years old.) i know them inside and out, and i love each episode deeply. sometimes, when something gets its hooks into you at an early age it's never going to let you go.
but there are others. i was a big fan of a lot of the apogee games: cosmo's cosmic adventure, wacky wheels, halloween harry (scared the shit out of me), duke nukem i and ii, etc. i also loved skyroads (that soundtrack), epic pinball (creepy android made an impression), jazz jackrabbit. i also loved all of the wizard games - weird text-only simulator games like one-nil, grand prix, greyhound and rockstar. i must have sunk hours into those games - they were a big influence in the type of games i tried (and failed) to make in qbasic as a kid.
god what else. i know this was the intended effect, but dare to dream actually does feel like a fever dream even when i play it today. my brother and i still play capture the flag by richard carr sometimes. i have committed every answer of rosemary west's iq challenge to memory. liero was always a big hit with friends. i dunno, that's probably enough? you asked for one and i gave you many times that so apologies, haha.