Cool game. On my first play I encountered an annoying issue though. The meteor was bouncing almost vertically, slowly moving towards my portal, but it changed direction slightly after a few bounces and bounced towards the tower again. It went back and forth indefinitely, at least I think indefinitely, didn't watch it for too long ;-)
Edit: Ah, didn't read the instructions fully, using SPACE resolves this effect. But still, it's a bit weird.