They come from the North, and they're about to invade your Nintendo DSi system. Beware of Olaf the Viking and his motley crew. Even now, their drakkars are sailing up the rivers to attack your castles. It's up to you to construct fortifications to prevent them from pillaging everything you own. The more you defend yourself, the more ferocious they'll become. Before you know it, they'll be invoking legions of fantastic creatures straight out of the mythical land of Asgard. Fortunately, the experience you gain will help you to build even more powerful defenses. Thwart all your assailants' ruses and unlock new kinds of buildings: tornado-blowing windmills to repel the ships, monoliths that strengthen your fortifications or canons that shoot studded shells. Discover more than 10 levels, tons of units, a Campaign mode, a Survival mode and three difficulty levels. There's even a little surprise at the end. Can you rise to the challenge and stop Olaf from taking your treasure home to his sweetheart Olga?