One Piece: Unlimited Adventure tackles two challenges, and it does so reasonably well. First and foremost, it offers a good amount of fan service by way of its flashback-oriented storytelling. Second, it's a somewhat-entertaining action-oriented adventure in it own right, with a light but amusing combat system and some fun boss battles. It's also quite long, though that's partially due to a lot of dull backtracking. This is a good game, to be sure, but a bit of monotony moves in early on, only to take up permanent residence as the adventure continues.