The creators of this video and project describe it as a "game," which it isn't, really, but it is really, really cool: you make a sort of extra-firm Jello-like product by mixing water, agar agar, and some food coloring (optional, but why wouldn't you want your final product to be blue or pink?) in a mold. After it firms up, you put it on the "game board," actually a capacitive sensor with an embedded Arduino microprocessor, which detects different kinds of touch on the Jello mold and converts it into theremin-like noises. Fun (and a little appetizing)! Video below.