My first formal Physical Computing project was simple- with an Arduino wired up, I coded a basic Rock, Paper, Scissors game.

With three possible inputs corresponding to rock, paper, or scissors, the project allowed players to compete against a computer adversary who was pure logic. The game took a bit of creative coding, but I got it to work. And play was straightforward if not a little too straightforward to be truly fun. What one realizes in coding up Rock, Paper, Scissors, is that when the logic of a game comes down to a computer randomly throwing one of three choices ('cuz that's how primitive I coded it) then there's really no agency in the game, just luck. Consider for a moment how much more interesting a game is when you feel like deception and your knowledge of the other player influence your choices. A better game indeed.