Here are some of mine:
I’m going to change the requirement to older games I’ve liked, although my definition is a little different and my choices are probably reflective of that -
Dizzy
R-Type
Elite
Wonder Boy III The Dragon’s Trap
Turrican 2 The Final Fight
The Secret of Monkey Island
Supercars 2
Kick Off 2
Eye of the Beholder
Captive
Xenon II Megablast
The Chaos Engine
and probably a lot more…
Probably just a few for me…
Battlefront (both 1 and 2)
Gauntlet Dark Legacy
SimAnt
Destroy All Humans
Ratchet and Clank 2, 3 & 4
mario kart 64
metal slug 2
castlevania 2
sonic the hedgehog
Where are the real classic PC gamers??? I played this on floppy disks and it was my favorite game as a kid.
Did seriously nobody mention The Legend of Zelda: The Minnish Cap?
That game was <3, huge for a GBA game too!
Secret Of Monkey Island was a great game as well
Ben 10 Protector of Earth for Nintendo DS. A pure masterpiece.
Ultimate Spider-Man for DS was quite fun too.
those are the two highlights of my gaming childhood lol.
Alright, I’ve decided to sort it by platforms and games that I’ve played
SuperNES
Super Bomberman 3 - It’s a tough one since there’s so many good games. I’ll give it to Bomberman due to all the good time I had with friends.
MD/Genesis
Shining Force II - One of the best tactics hidden gems, many have not even heard of it.
Playstation
Castlevania: Symphony of the Night - The Masterpiece.
Nintendo 64
Pokemon Stadium - I’ve only played a few N64 games, the minigames were super fun, it was my Mario Party because I didn’t care for Mario as much as Pokemon at the time.
GameBoy Color
Pokemon G/S/C - My favorite generation, the mechanics that it brought at the time was mindblowing for me, like wooot you can have a phone in the game?! P.S. I didn’t have a phone irl then. 
Dreamcast
Sega GT - Another console that I didn’t had played a ton of games, I’ve only even had the experience because a friend of my uncle lend him the console to try. Dreamcast, GameCube, all were “rich boy” consoles. Also, Dreamcast was smooth, it run close to 60 fps I believe, it was something that I never experienced before with consoles.
Playstation 2
Grand Theft Auto: San Andreas - Ahh, all the time well spent playing this. Wreacking havoc with a friend dressed as a prostitute, those were the days. Completed the story mode twice, and I need to complete a third time on Steam version, lol.
GameBoy Advance
The Legend of Zelda: The Minish Cap - One of the not so popular Zeldis, but a favorite of mine. Also a tough choice since there were really good GBA games as well, I would give it to FFTA, but I’m going to give it on the next category!
Nintendo DS
Final Fantasy Tactics A2: Grimoire of the Rift - The sequel to the GBA one, if you know me, I’m a sucker for pixel graphics, and this game was beautiful. And all the FFT mechanics and fun. Stole the spot from many games for me.
PC
Diablo II: Lord of Destruction - Oof, there are so many, such hard choice. But I gotta give to my boy. Still hoping for a remaster, even though it’s not necessary. 
