Thanks for playing and thanks for the feedback! Really good to hear you enjoyed it.
I very well understand your comment about the music. It would have been nice to have longer track or even multiple different songs but I had to also do programming + level design which were higher priority. That's what I managed to do with the time I used for the background music. I'm just glad that there is at least some music! But if I were to continue working with the game later, music would obviously be one thing that needs more content.
The game only has 4 actual levels. That's the amount of level I had time to design and test. The fifth area was meant for "narrative" closure of the game: the death of the character which is represented by the screen going black. So that's how the game currently ends but I can see why people would be confused about it. I think someone else also commented earlier that they thought it to be a crash.