Those darn invaders. Just when you sit down to enjoy a nice cup of coffee and a newspaper, they always show up to batter the front gate. They're reliable like clockwork, that way. Of course that means you have to put everything down, man the siege weaponry, and remove your enemies from the medieval gene pool. As enjoyable as this task sounds, the new iOS game Siegecraft does its best to suck the joy out of skewering folks with giant crossbow bolts or flattening them with catapult ammunition.