Lego Homemaker Maxifigures and Lego Fabuland animals travelled to the future from 70's and 80's. They found Mindstorms race cars and Fabuland pigs decided to race each other. The rest of the time travelling bunch are rooting for them.
There is a color sensor mounted under the NXT brick. Players shoot balls up the steep hill. There are holes on the top. If they're succesfull the ball goes down, the color sensor detects the color (blue or green) and the car moves a bit further. Whoever reaches the end of the lane first is the winner.