I am working on such a game with the same concept but better pathfinding and game performance but it will take some time before I can come up with something for you guys to have a look at.
This is his first game. He used a well known tutorial game for it. As long as he will improve, I think for this first one we can call it ok. Keep practising and you shall get better in producing tower defence games.
keep practising flash, and you shall do better next time. good effort. i give you 5/5 for your newly added "restart" button. that shows that you care for the community and you want to improve yourself.