Firstly, the soundtrack for this game is worth $9.99 on its own, it is amazing and atmoospheric and having the soundtrack available as a free download is an excellent extra.
The game is also great, it brings back memories from when I played it on the PS1, it is a challenging 2D puzzle-platformer, but frustration never sets in because of the difficulty for one reason: everytime you die you know it was your fault, you can see how to acomplish almost every puzzle and the only limit on your progression is your ineptitude.
The game is set in a fantastic and original world and all of the characters are lovable and relatable and different. The only drawback of the game is a short, unskippable death sequence, but it is only a slight niggle with an otherwise brilliant game.