I played most of
Minish Cap through on a GBA emulator a couple of years back and it was excellent. Obviously not quite as good as with proper buttons but the judicious use of save states in the harder dungeon rooms takes the frustration away and I'd have happily finished the entire game on my phone if not for a nasty crash bug on the last dungeon (which hadn't been fixed on any emulator at the time).
I was focussing on SNES/GBA games at the time and Minish Cap aside I struggled to find games that were both decent and playable on the phone screen. By which I mean anything that didn't really rely on the shoulder buttons too much because they're close to unuseable with on-screen buttons; you can't hit them while still using the direction pad/ABXY buttons like you can with a proper controller y'see. For instance, having never played a Metroid game, I really wanted to get into Super Metroid but it was rendered unplayable almost instantly because it used L or R as a modifier key to shoot missiles (I think) which were a core part of the game. I'm not a big retro gamer so there wasn't much left I felt stood the test of time
and worked well without proper hardware buttons. Although I'm happy to be corrected on that if anyone else has some better recommendations for you.