This is a distributed game that uses peer-to-peer architecture. Each player is a peer.
The game uses Rock-Paper-Scissors-Lizard-Spock rules, originally described there.

We use libp2p. What is Libp2p?
Good question! Libp2p is a set of protocols, and libraries, that allows to easily build peer-to-peer applications. In other words, it is a middleware for peer-to-peer systems.

libp2p peers are addressed with combination of unique PeerId and listening address, which is regular TCP address/port combination.

libp2p manages communication between peers. It provides a convenient publish-subscribe channel abstraction. We use gossip protocol to make messages reach all peers.

Games hold between peers in the same network. Peers can discover each other with mDNS. When a host starts, it creates a PubSub channel, that will be used for game. It will automatically receives new messages from the game topic.

When a peer wants to launch a new game, it publishes a special message into the PubSub topic. To start a game, all players who wants to participate should send a vote for starting game.

If all nodes voted for starting a game, game starts. Players who had not voted can be kicked.

When the game starts, each node should do following:

• create a symmetric key
• choose his move (Rock, Paper, etc.)
• send message with encrypted move

After node receives moves from all other players, it sends the key to PubSub topic. If some node did not send move or key within a certain timeout, it can be kicked.

Kicking forbids player to take part in games in this GameRoom. Node can start voting for kicking other node by sending a special message to PubSub channel. Then all of the players can vote within a certain timeout. If majority votes. node will be ignored and no players will accept messages from it.

When node knows moves of all players, it performs topological sort to determine who won a game.