To add an online multiplayer would involve using networking, which is an advanced topic that requires an entire book to clearly explain everything that is required.

However, we can add a local multiplayer to our games, allowing more than one person to play together on the same device in the same location.

There are multiple ways of doing this:

Pass and play is very simple because the game functions as a single-player experience. The only difference is that we would need multiple separate profiles or sets of variables to store each player's data.

Real time is slightly more complex, requiring us to create multiple GameObjects in the scene to serve as the characters for each player. There is also the separate set of data for each player and each player's own separate and specific game controls. For instance, we can use the WASD keys for player 1 and the arrow keys for player 2, and so on.