Great stuff, but the biggest problem for me was that I couldn't grab a new part, deposit it at the launch pad, and then go find the next one. By the time I had collected the 4th part, moving was getting pretty slow and annoying because I can't roll around anymore. I would probably suggest the above (being able to deposit the parts you've collected at the launch pad whenever) as a solution to that. Loved the music and the use of the enemy as movement inhibitors, rather than the usual 'attacking your health bar' :).