I just started playing Phantasy Star for the Sega Master System. I haven't gotten very far yet, but so far it's as good as I remember. For it's age, it's actually pretty impressive. The surface world is a mostly standard top down RPG with a couple of twists that were a few years ahead of their time. While the dungeons are a 3D type of crawler with some really complicated mazing in the later parts of the game. The battles are a bit simple, but that's OK with the tiny n810 controls. I never finished the game as a tyke, because my system broke, but I've always wanted to, and now I can. I don't remember the story at all, so it could suck or be great. I just remember that the multiple attacks later in the game were BA. I was so stoked when I stumbled upon a Master System emulator for maemo that I dropped all of my other emulation stuff for this. If you do try the Sega emulator, use it in full screen mode. It's a bit jumpy in windowed mode.

here's the direct install link if you want it