This is a really cool concept! There's a lot you can do with the boomerang and teleportation mechanic, and the gameplay does feel pretty good. I had a real 'eureka' moment when I figured out that I could only get past the first tutorial enemy by rushing it, and that trying to dodge shots and snipe enemies at longer distance wasn't going to work.
The graphics are very simple, but honestly I kind of like them. Nothing wrong with an abstract platformer. The sound effects worked well, though having some music would've been cool.
The difficulty was a bit too rich for my blood, though I think that's mostly because I'm not really the target audience, since I'm not very good at platformers. You have to have very fast reflexes for this game. You could consider putting a few checkpoints into the levels, or maybe give the player a little more time to react.
All in all, though, this was fun!