Vikings is a strategy game with a dash of action. Deep down it feels like the classic Pirates! set a few hundred years back.
You take the role of a viking ruler. Its up to you whether you decide to stay and rule over your province (good for the province) or go out and trade with/raid other areas (good for wealth, fame). Along the way you can get yourself married, go on quests, get in bar fights, and in general get into all sorts of viking fun.