Rock, paper, scissors
Everybody knows the rules. What makes it a game rather than a coin toss is that both throws are sealed and revealed together, so nobody can react to the other.
The rules
- Rock blunts scissors, scissors cut paper, and paper wraps rock.
- Both players choose at the same time, in secret. Neither throw is shown until both are in.
- The same throw from both is a tie, and the round is replayed.
- A match is best of five, so the first to win three rounds takes it.
Because it is played by correspondence, your throw is sealed the moment you make it and cannot be changed once you see theirs.