Roll the two dice as many times as you like. Safe rolls add to your pile. Bank the pile to keep it.
One lobster (a 1): your turn ends and the pile is gone. Banked points survive.
Two lobsters: turn ends and your whole score drops to zero.
Doubles (not two lobsters): the pips count, but you must roll again — banking is locked.
Getting in: your score stays at zero until you bank 21 or more on a single turn.
Winning: first to bank 100 takes it.