Awsome game
personally I say it was challenging ((I even used the buying a bunch of soldiers technique))
personally I say the castles ability to attack you should be effected by how damaged it is ((I've seen it firing a bunch of arrows even when the front wall and quite a bit back was gone))
also I would of liked to see a "Deploy all" button to deploy all your troops at once ((Since the F keys didnt work for me and it would make it much quicker to get to the action))
All in all great work