Find a medium-sized box for your game.
Flip the box over and cut two doors on the bottom, as well as an access hole through the top.
Construct your circuit: power -> wire -> sound trigger -> timeout -> buzzer -> lightwire
Mount your Bits in the box. Hide the power & battery inside - then mount the sound trigger just above the target door on the far side of the box. Run the wire out and mount the timeout, buzzer, and lightwire on the outside of the box.
Adjust the timeout Bit to provide the appropriate amount of celebration for each successful shot. Use the lightwire to decorate the box.
Hang a bell inside your box, just in front of the target door on the far side of the box. The sound of your ball hitting this bell is what will set off the celebration, so make sure that it hangs inside the doorway, close to touching the floor.
Now we make the ball. Get a styrofoam ball and cut it in half; put a quarter or some pennies right in the middle and tape it back together. Be careful! If the coin isn't right in the middle, the ball won't roll well.
Decorate your game and then test it!