This game has potential, but you need to manage the attack patterns. Can't depend on random, cause sometimes feels unfair when attack from all sides at the same time and can't rewind them.
With a little tweaking, the game can become much more interesting. A while ago I did a game based on everything random, and things just go wrong.
As other users said, for a first game it's a really good work. And you manage to finished in time.