A strategic press-your-luck game of rolling dice for points.
The name is derived from the old Norse word "perthro", which means "dice cup", and is also the focus of the game: rolling (throwing) dice to get pairs of numbers.
Players roll 9 dice, set aside any matching pairs they want to keep, and then re-roll the remaining dice. Points can only be scored for pairs of numbers, and pairs must be formed on the same roll. If no pairs of numbers are rolled, the turn ends and the dice are passed to the next player.
Scoring can quickly get intense, as multiple pairs of the same number are worth bonus points, and getting 4 pairs plus a matching number on the "extra" dice allows players to re-roll all 9 dice again.
When a player earns a total score of 500 or more, all other players get one last turn to try and get enough points to surpass that score. Once all players have received a final turn, the player with the highest score is the winner!