Thanks for the feedback. I agree with your complaint. The pacing is still too fast. I would have loved to implement a small countdown before the start of each wave and the checkpoints are a nice idea. I wish I would have started programming before Sunday, I really could have used the Saturday :D
But as a major lesson for my first game jam here, I learned that I should take a day leave before the GameJam so that I don't feel tired from the work week (which is already programming for me) and loose my motivation on Saturday. I was almost giving up but Sunday got me hooked again and now I'm really looking forward to more game jams.
Thanks for the constructive feedback, this motivates a lot.