Beat the last stage, and subsequently the last boss and the game. It's a nice change of pace that the last stage is presented like one long level, rather than a hub, with several smaller challenges. There are, however, a couple of points that were pretty irritating about this level specifically. The main thing that I would complain about the final stage is the difficulty: while not impossible, and not the hardest that I've ever played, the fact that the entire level was far more difficult than any that had come before it, especially during the platforming sections, was definitely off-putting. The other major problem comes in the form of the last boss himself: simply put, he was a real pain to get through. The main problem is not necessarily his difficulty, although the problems stem partially from it, it is the fact that there are no checkpoints throughout the entire battle. The boss himself has 3 forms: 2 shooting stages and a platforming stage. The first and second stages are pretty easy once you learn his pattern, although the fact that after you die once, you can never get hit, tempers this somewhat. The third part, on the other hand is incredibly challenging, probably the hardest section in the game, as it probably should be, considering that he is the last boss. Unfortunately, the lack of checkpoints means that every time you mess up during the platforming segment, you get sent back to the first shooting section, causing much frustration. In spite of these problems, I must admit that the entire level, including the boss, is well designed (apart from the aforementioned lack of checkpoints), and overall, I had much more fun than frustration playing this area.