Definitely the ones that simply aren't available. If I ever get my PC upgraded, I know I can download emulators, but in the meantime, several incredible games are simply not playable. Since I was an Xbox kid I am currently revisiting:
- Jet Set Radio Future
- Ninja Garden Black
- GTA: San Andreas (the original, far-superior one. It didn't add visual/gameplay glitches and all the amazing songs are still in it, unlike the "Definitive" Edition)
The thing is, my old consoles still work. It's the controllers that are bad. I have dozens of original Xbox, 360, PlayStation 4, and Xbox One controllers that drift, are flat-out broken, or a button is just wonky. My solution? An adapter that lets modern controllers work with old consoles! I use the Brooks Wingman XB2, but there are others. My favorite controller ever is the Xbox Elite Series 2. It is not just customizable, but sturdy and has outlasted many of my other controllers. So now I can play retro games, wirelessly, with zero latency, with turbo functionally!
To be perfectly clear, I have no affiliation with either company and gain zero benefit if they double in profits, or die out and close up shop. I'm just a fan...