Step 1: Materials
-Computer with Scratch Programming (free online and offline versions)
Step 2: Game Board
This is a super simple Whack-a-mole game. You could make this as complicated as you want; I was going for fast, easy, and used what I had around me.
For the three "mole" spots I made three foil rectangles and used a sharpie to write "whack" "a" "mole".
For the hammer I initially wrapped a Popsicle stick with aluminum foil and attached a foil rectangular prism for the head of the hammer. However, as the day progressed I found it was more satisfying to simply hold the foil Popsicle stick in one hand (this is the ground for your Makey Makey) and hit the mole foil pads with my other hand! You could even make a real hammer with a plastic kid's toy hammer covered in foil, that would be sweet.
Since my game was set up in a public library space right next to a work desk, I folded paper and put it under the foil mole pads to deaden the smacking sounds. I attached the jumper cables to each pad from the Makey Makey and then scotch-taped the pads down so they wouldn't move around and would survive a little better.
Step 3: Scratch Programming Game
For the Scratch programming I used an already made remix by tarmelop found at this link. You can make your own on Scratch from scratch, remix this one, or just use one someone has already made! Sometimes there is no need to reinvent the wheel :)