Asklemmy

Kolibri for the Sega 32x addon for the Genesis/Megadrive. Most of the reviewers that weren't down with the game either complained about the difficulty or lack of story/making sense, but it was a beautiful game for the time that took the space shooter concept and made it into a game that was somehow chill while also being difficult enough to sometimes momentarily make you want to rage quit. If you enjoy games like the Raiden series, you'll enjoy this.

Shout to Knuckles Chaotix (the most unique take on Sonic gameplay of the classic 2D era) and also Shadow Squadron (very Star Fox-esque), which are also slept on because 32x.

Exclusive to the Genesis/Megadrive, it's a crying shame that the Vectorman games never received a third iteration and have seemingly disappeared into the grey goo of IP purgatory. Vectorman and Vectorman 2 were amazing for the time: they were arguably the best 2D platformers of the era, graphically beautiful, oozing with charm, and with an amazing soundtrack to go along with it all. It's crazy that the developers were able to squeeze the performance they did out of the hardware and playing emulated versions of it now still doesn't compare to how it feels and looks playing it on the original hardware with a CRT and a nice sound system (but you should still check it out absent that setup).

On PC, also from the 90s, Descent was truly groundbreaking and unique. It's an FPS that said "what if you were playing as a space ship and had six degrees of freedom to move about?" It was also the first truly 3D FPS game.