What starts as an orderly tower of 40 colored dice devolves into a frantic free-for-all when you play Tenzi ($14.99 at Fantastic Kids, 1503 Third Ave., nr. 85th St.; 212-452-1048), a new fast-rolling game invented by two local admen. The rules are simple: Claim your color, roll the dice, choose a number, and then keep throwing until each one lands on your specified digit. The first to do this—and to shout “Tenzi!”—wins. Sound too rudimentary? There are infinite iterations of the game, including Tenzi Tower, a kind of Tenzi-Jenga hybrid, and Stealzi, a twist that involves pilfering other players’ dice.