The Knattleikr ball game was very popular amongst the Vikings. It was one of the roughest games invented, and often deaths were reported from the games;

Viking writer Hord Grimkellson reports at the time of a game between Sands and Botn, that "before dusk, six of the Strand players lay dead, though none on the Botn side" Apparently Tord Blig was the worst, as he was barred from playing completely due to his "bad temper, even though he was not so strong as to be excluded for that reason"

Apparently the worst berserkers where thrown out of the game even in those days. From west-Iceland it's reported that at Lekskalvollane ("Ballgame Shelters") there were annual tournaments that lasted 14 days. Shelters were erected where people lived during the tournaments. The place still bears this name.

Today no one knows the game's exact rules but there is some information. We know that: