First, absolutely beautifully made game. I wasn't sure what to expect given the authors comments I was really pleasantly surprised. I think the story came across fine, and I didn't really think the game needed to be any longer (though I would have enjoyed the extended play it if it was). I do have a few comments/things I noticed though:
1. The control layout was not so hot. I got used to it but it definitely could have been better. Try switching to a small grouping of keys (asd, cxv, etc.)
2. Before collecting the ball I accidentally pressed throw and became unable to move. I restarted and didn't have the problem again (though I was able to reproduce it.
3. After collecting ball, but before realizing I can't go home I again accidentally pressed throw, became unable to move same situation as number 2 basically.
4. Some people need/want to play muted, this can be a problem given there is instruction in the vocal aspect of the game. Also some of the conversations are not super clear. Consider adding subtitles, it would fix both of these problems.
5. After introduction to 'Mushroom' trampolines I missed third trampoline, guy went into climbing position and was stuck. I restarted and made it past, but again was able to replicate the error.
6. In the level before the last if you overshoot the trampoline thing there is no way to get back save suicide. You may want to consider a way to get back, even if it isn't a way up. Because the first part of the level is a bit time consuming.
7. The end screen just blanks, Try setting it to return to the title.
8. Considering the number of times I had to reset because of bugs or getting stuck, and especially if you intend on expanding the game you may want to think about adding either a restart level button or a button to return you to the menu. As things stand I had to restart the game (close the window and restart, not start over from the beginning) each time to get back to being able to functionally use level. Yes, I liked the game enough to do that six or seven times.
Ultimately, this is well worth playing, has a wonderful atmosphere and story, and the graphics are very nice and fitting for the game. The game could use some minor tweaking, but I am certainly not complaining, I look forward to seeing more from you. Keep up the great work. 5/5 10/10