http://www.xgenstudios.com/play/castle/
Attacks come at dawn. The Barbarian invaders arrive in relentless waves until nightfall, when they return to their camp... or sleep in your castle, if you are not capable of defending it. Luckily, however, you have a few other tricks up your invisible sleeve. For instance, the capability to convert enemy troops into soldiers to help you defend your walls. You can also purchase upgrades and repairs for your castle, and miraculously, they can be administered overnight, while the barbarian hordes are snoring in their camps!