Well I played for a few hours until i got the best second score of the game XD
It's really addictive, and the fact that you guys made all this game in 8 weeks it's really impressive. You should start a kickstarter project or something like that, i really want to thank you by helping the project.
I only found a few bugs at the end of the bigger waves, the aliens got stuck in some pillars or between the boxes, and it was annoying to try to find them while i wanted to finish the challenges. But that's the only problem I found.