Loved the concept as it fixes one of the main complaints of the tower defence genre, that being that theres not a lot to do during the waves. This allows the player to remain engaged at all times which really increases the fun factor for me.
Loved the art and audio design, it fit incredibly well with the kind of game you wanted to make.
The only drawbackto this is that while its a very fun and polished game, I don't really see it fitting the theme too well. But as a game, I think you did a great job.