There is a lot people are missing here
I really like this game. I don't understand what people mean by unresponsive controls. I experience no lag. Yes, there is a large difference between how fast monsters move on the ground as compared to how fast they move while jumping, etc. A turtle moves slowly. A jumping monster can't walk, he can only hop. A hovering UFO can't stop on a dime.
Also, there are differences to every level beyond the music and the background. There are "special buildings." Upon demolition of these buildings, there are changes that can make the game harder or easier. This made the game very fun for me and added great replay value.
All-in-all a great game, especially for a programmer's SECOND game. Keep going, your next game will be even better!