Octo is a press-your-luck dice-rolling game where the goal is to set, and then maintain, a high score. Once a player has set the score, it's up to the rest of the players to beat it--and then become the holder of the score themselves. Players start with eight six-sided dice and roll them all at once, then must set aside at least one of the dice rolled. They may then stop or reroll all dice not set aside. The caveat is that the same face value may not be claimed more than once per turn; once you've set aside two sixes, for example, further sixes you roll cannot be used. If you roll and cannot set aside any of the dice due to them matching previously-rolled values, you bust. Octo is one of several games Reiner Knizia describes in his book Dice Games Properly Explained.