Another App Idea
Have a game of electronic (or just electric) circuits. Give the player a few parts, as many wires as needed, and a goal. The player attaches the parts until the goal is achieved. The simplest case would be a battery and a light bulb, with the goal being to light the bulb.
Other basic components can be added, resistors, caps, diodes, LEDs, etc. The game would involve only simple circuits, to make it easier and to make modeling the results from the circuits the users make easier.