Definitely one of the best indie games. As a fan of the old NES Megaman and Castlevania games I really enjoyed the gameplay with multiple weapon 3-level upgrades and sidescrolling cave exploring. Things start getting even more interesting and trickier when you get the Booster, which is a jetpack of sorts. Add to that a touching story that makes you care for the characters, where your actions & decisions shape which ending you get. I already had played the free version, but Pixel, the sole creator of the game, definitely deserves the money. Plus, there's extra content! A must-play.