I played the first game for hours on end
Theatrhythm Final Fantasy really surprised me. It was like the perfect combination of good design and extra nostalgia thrown in for good measure. That's why I can't wait for Curtain Call, the follow-up game that looks like it's just more Theatrhythm, which is fine with me!
Some highlights include a ton of extra tracks, multiplayer, more characters, and songs from Lightning Returns and Final Fantasy XIV.