What's tricky is some old classics are probably still worth playing, but some are unplayable by modern standards. I was looking into old games, and Descent just seems too hard, Myst-style point-and-clicks don't work. Older RPGs feel like too much work. I also have zero interest in playing the same level for two hours because of some especially hard gameplay element.

For FPS, see if you enjoy Doom 4. If you enjoy Doom 4 then you should be able to enjoy the whole line of Doom 1/2 - Duke Nukem 3d - Quake 1/2 - Unreal that I consider as the golden age products. Unreal has the most advanced engine and the community releases a few patches back in the day, so you might want to watch a few videos and decide which one(s) to play.

For RPG, there are a few "ages". Check out Ultima 1/2/3/4, Wizardry and Bard's Tale which I consider still fun to play despite the oldskool graphics. If you can't stomach the style or graphics, check out SSI Golden Box products. If you still can't go through any of the above, I'd suggest you try out Fallout, Baldur's Gate and Neverwinter nights (Both Neverwinter nights and Baldur's Gate have an enhanced edition that you can purchase).

Even back in the day Descent was more of a niche game. I played a crap ton of it on the Kali ladder as well as modem death match with a buddy, but we were the only ones out of our extended friend group that liked it vs everyone that was into doom, quake, etc. A lot of people got motion sickness issues from it and couldn't really do anything about that.

If you're interested in Myst style games but want to play a modern spiritual successor, check out The Witness. It's an astoundingly well designed game, though some of the last puzzles will take some persistence.