Wow, you totally nailed the boomerang, it's super fun and satisfying to use, killing multiples slimes in a row with a well timed shot is incredible. At first I was thinking it would have been hard to use the boomerang but since it bounces off the borders of the screen it make the whole things super manageable. I was fearing I would have to endlessly chase the boomerang but it was not the case.
Only complain would be that there is no music and maybe that sometimes slimes spawns at bit too much into your face (mainly blue slimes, that's more noticable since they are fast)
Great entry I had good fun with this one.