Having rounds, round 1 = 15 drinks... round 2 = 20, etc... different customers want different drinks? Testing my lemon knowledge... drink with ice, umm strawberry lemonade, lemonade and coke? stretching it I know... the further rounds different speeds of customers? Maybe increase the number of lanes? Have government ppl come in a lane and you have to avoid them? Use the monies collect to buy different equipment, increase drink production, or hire staff? The world is your lemon my friend, squeeze it for all its worth! :)