I really liked the how the game looks and sounds.
It's fairly simple to understand how to play once you read instructions on the web page. I felt like the enemies didn't scale that well compared to player. After about 2 minutes of playing, I had strong enough defenses that were never truly tested.
I think there should be some new mechanics and new enemies introduced later in the game. As of right now, you see all that it has to offer in the first few minutes and the remaining time until 15 minute mark is a bit repetitive.
Still, I'm happy I played this game. Great job!