Old games? Let me throw Final Fantasy Tactics in the mix. Easily my favorite game of all time and one of the only ones I consistently come back to, despite releasing in 1997.
If you’re not familiar, FFT is a turn-based tactics game which is very different from other mainline FF games in a lot of ways. The story is one of the best, if not the best, in the FF series. For gameplay, you recruit and manage soldiers which progress using a fairly in-depth job system which is also pretty easy to pick up.
I’m sure you could find a PSX emulator of the original but, honestly, I really recommend the updated War of the Lions edition they did for the PSP. It’s been ported to mobile and is actually a great port. My one tip for anyone who tries it is to make multiple save slots in case you find yourself overwhelmed in a story dungeon/encounter.
I recently picked up Midnight Suns which, to be very clear is not FFT. However, I will say despite the kind of bad story and corny aspects of it, the actual turn based combat is excellent. I thought I would hate it being card-based but it really grew on me a lot. Definitely scratched the FFT itch.