needs a lot of work but is pretty cool this would be perfect for a addicting little game on your smarphone on the bus or train for example maybe more upgrades would be cool though

Really neat idea!  Other than the lag/memory leak, the one suggestion I would make would be a way to get more planets or upgrade slots or something.  Around the second wave's arrival, I had a bunch of wasted turns because I had already met the defense goal and used all the space on all five planets in my hand.

Excellent little strategy builder with a fun long and short term game loop.