Really cool simple idea. It's the sort of arcadey game that really needs a bit more juice, some extra mechanics and maybe some background music. A couple different enemies, some way to remove enemies, I kinda like the flying in loops and not having weapons so maybe the enemies could get confused and crash into each other or something like that (although that idea definitely needs workshopping and testing) and a bit of juice and you could have a great game, but even without that this is a very solid submission.
*EDIT there is background music. My headphones weren't working. I just assumed you didn't add it sorry"
Would also love it if you could play my game and let me know what you think!