I really like the core mechanic of the boomerang throw! It's just the right level of 'airy' and it has a small enough cone of possible paths to go through to allow for accurate timing to get to where you want to go. This would be a great mobile game as well as PC game, which is what I assume you're going for.
A few comments:
- You should remove the brown rocks and trees, or at least make them pop less. I struggle with figuring out what were the walls and what were garnishes. There should be more contrast.
- I too would get confused on what the failure state was. I like having 3 attempts before I have to restart the level, but I was confused on that even. Maybe add to the UI number of hits you're allowed before you have to restart, and make the restart more obvious that it is happening.
Overall its solid, I could see this working.