SUI Move Official Example Contract Practice - Game Category: Shared Object Tic-Tac-Toe (shared_tic_tac_toe)

Introduction

This guide explores the implementation of a decentralized Tic-Tac-Toe game using SUI Move's shared object model. Unlike centralized versions requiring admin-mediated moves, this approach enables direct player interactions via shared objects.

Key Features

Decentralized Gameplay: Players update the board directly in a single transaction.
Shared Object Model: Eliminates intermediary steps, reducing operational overhead.
Simplified Logic: Streamlines gameplay mechanics compared to traditional implementations.

Contract Code Highlights

👉 View Full Contract on GitHub

Core Functions

create_game
Initializes the board as a shared object with two player addresses.

public entry fun create_game(x_address: address, o_address: address, ctx: &mut TxContext) {
    // Initialization logic here
    transfer::share_object(game);
}

place_mark
Validates player turns and updates the board. Emits GameEndEvent upon completion.

public entry fun place_mark(game: &mut TicTacToe, row: u8, col: u8, ctx: &mut TxContext) {
    // Game logic and winner checks
}

delete_game
Destroys the game object post-completion.

public entry fun delete_game(game: TicTacToe) {
    object::delete(id);
}

Prerequisites

Account Setup

Alias	Address (Sample)	Role
Jason	`0x5c588...569a`	Game Creator
Alice	`0x2d178...2d19`	Player X
Bob	`0xf2e6f...09f0`	Player O

export ALICE=0x2d178b9704706393d2630fe6cf9415c2c50b181e9e3c7a977237bb2929f82d19
export BOB=0xf2e6ffef7d0543e258d4c47a53d6fa9872de4630cc186950accbd83415b009f0

Deployment Steps

Publish Contract
```
sui client publish --gas-budget 100000000
```
- Record PACKAGE_ID from output.

Initialize Game

sui client call --function create_game --package $PACKAGE_ID --args $ALICE $BOB

Note the shared GAME object ID.

Gameplay Walkthrough

Player X (Alice) Moves

sui client call --function place_mark --args $GAME 0 0

Player O (Bob) Responds

sui client call --function place_mark --args $GAME 1 2

Continue Alternating Turns
- Repeat until a winner emerges or the board fills.
Game Termination
- Trophy awarded to the winner.
- Delete the game object:
```
sui client call --function delete_game --args $GAME
```

FAQ

Q1: What distinguishes shared object Tic-Tac-Toe from centralized versions?

A1: Shared objects enable direct player interactions, removing the need for admin-mediated moves and reducing transaction steps.

Q2: How are winners determined?

A2: The contract checks for three consecutive marks (X or O) horizontally, vertically, or diagonally.

Q3: Can anyone delete a game?

A3: Currently, yes—though permissions can be added to restrict deletion to players or admins.