Adding Multiplayer: Server Logic

by Hexagon, 2 minutes read deno tetris guide deno-tetris-guide

Welcome to part five of our Detris series. In this article, we dive into multiplayer action, where we deal with multiple players, and real-time updates. Buckle up!

Adding Multiplayer: Server Logic

To implement the multiplayer modes, we mainly use the following files:

  • game/modes/coop.ts: Co-Op mode
  • game/modes/battle.ts: Battle mode

The actual files are found at

Let's go through the differences compared to single player mode:

Player Management

In a single-player game, you're only concerned with one player's actions. In a multiplayer game, you need to handle multiple players, each with their own game state. Create a players array to keep track of connected players.

players: Player[];

Game State Sharing

In single-player mode, the game state (grid, Tetrominoes, Position, etc.) is only for one player. In multiplayer, you'll have to manage and share the game state among all players.

Key Differences in Class Methods


In single-player mode, you initialize the game state directly in the constructor. For multiplayer, you'll initialize the game state for each player separately.


In a single-player game, you only need to check if there's one player. For multiplayer, you'll need to check for the required number of players:

checkRequirements(): boolean {
  return (this.players.length >= 2);

In a single-player game, you only broadcast messages to one client. In multiplayer, you'll loop through all players:

broadcast(m: unknown) {
  for (const player of this.players) {
act Method

The act method in single-player mode is straightforward; it directly manipulates the game state. In multiplayer, you'll have to identify which player initiated the action:

public act(player: Player, key: string, state: boolean): void {
  // Identify player and manipulate their specific game state
iterate Method

In single-player, the iterate method updates the game state. For multiplayer, you'll need to iterate over each player's game state:

iterate(): boolean {
  for (const player of this.players) {
    // Update each player's game state
  return true;

Wrapping Up

The main difference in adding multiplayer is managing multiple game states and player interactions. You'll need to keep track of each player's state, update it individually, and then broadcast the changes to all connected players.

That's it for now! You're now equipped to take your Tetris game into the multiplayer arena. Stay tuned for more updates!

Implementing Single-Player Mode: Server-Side Calculations Creating AI Opponents: Dive into the Code