Circuit 1:
Circuit 2:
Circuit 3:
Question 1:
Besides buttons, there are other kinds of sensors that could takeover, and the game would also run. For example, pressure sensors. When we press on it on Arduino, it could also count and decide which player wins the game.
Question 2:
We use a 10K resistor in order to prevent the occurrence of short circuit, which would harm our microcontroller and Arduino.