I stopped trying to actually kill the enemy, and started imagining my ship trying to circle them with an imaginary rope. So all I did was keep forming a perimeter and circling them (while staying closer to the edges). Worked like a charm on lvl 20!
"Why am I here, why am I speaking nonsense". I love meta-games that have an underlying theme, and some levels are interesting. But a few seem to have disconnected captions & gameplay.
PS: What's with the downvotes to (most recent) appreciative comments? :|