I really enjoyed the game, but I will say a thing I really enjoy about tower defense games is that you fill up the entire map with these towers and you just see a bunch of things flying around the screen and enemies moving. And I felt that the beginning levels felt like they were just about to reach that point and then the level ended.

I would've liked if you stretched out the beginning levels a bit more so we could get to that point but it was fun. Also I couldn't finish. Half way through I died in a level because I bough a lazer thing in the beginning and it didn't kill anything and I just died and then when I hit retry the game just didn't start.

Small bug but maybe you could look into it. I know when I had this bug in the past, it had to do with me not unsubscribing to events after they're destroyed but I don't know how you coded your game but that may be a place to look at if you did use events.