Thanks for comments, I appreaciate them all.
The depth cue is a sore problem. I think that 3D models for the collectibles, lighting and some distance cues or such would have helped a lot. Had no time to implement because of the problems I had with the sound.
I wanted to create the controls in such a way that the player needs to actively control the ship all the time and use timing instead of going straight to the right position (this does not help much now, that the right position is so hard to see :P)
The .NET framework requirement would annoy myself too. I don't know yet if I can go around it, bundle the required files with the game or target an earlier version that people might already have.
And thanks for the comments on music. I just made it so fast but seems I hit the spot well enough.
I am looking forward to next Ludum Dare and I hope I have gotten rid of the technical problems by then.