For the science fair I made two games using electric circuits. One consisted matching questions and answers. I made a list of questions and their answers on a panel and decorated it with plastic invertebrates. Next to each question and each answer I placed a metal binder. The questions were connected to their answers by wire on the back of the game board. Separately I connected two pieces of wires to two nails, a battery and a light bulb. The purpose of the game was to match each question to its answer and touch them with the big nails. If the answer was correct, the electric circuit would be closed and the light bulb therefore lit up. If the answer was wrong the circuit is would be open and the light bulb didn't light up.
For the other game I used a shoe box. I bent a piece of metal wire which I placed on the shoe box. Inside the shoe box I put a battery, a light bulb and a metal handle with a tiny loop at the end. The purpose of the game was to pass the loop along the bent wire without touching it. Everytime the loop touched the wire the circuit became closed and the light bulb would light up!
These are two fun games you can easily make with basic materials.