CLI Tic-Tac-Toe

A command-line Tic-Tac-Toe game built with F# / .NET 10.

You play as O against a random enemy X. Enter a square number (1–9) to place your mark.

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Getting Started

Prerequisites

• .NET 10 SDK
  Verify with: dotnet --version (should show 10.x.x)

Run

# Windows
run.bat

# Unix / macOS
chmod +x run.sh
./run.sh

# Or directly
dotnet run

Build

dotnet build

Publish Self-Contained Binary

# Windows x64
dotnet publish -c Release -r win-x64 --self-contained

# Linux x64
dotnet publish -c Release -r linux-x64 --self-contained

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How to Play

Board Layout

Squares are numbered 1–9 left-to-right, top-to-bottom:

 1 | 2 | 3
---+---+---
 4 | 5 | 6
---+---+---
 7 | 8 | 9

Empty squares display their number. Placed marks display O or X.

Taking a Turn

1. The current board is printed.
2. You are prompted: Your move (1-9):
3. Type a number and press Enter.
   • If the input is not a number in 1–9, you are asked to try again.
   • If the selected square is already occupied, you are asked to try again.
4. O is placed on your chosen square.

Enemy Turn

After your move, the enemy automatically picks a random empty square and places X. The chosen square number is printed so you can follow along.

Winning & Ending

Result	Condition
You win	Three Os in a row, column, or diagonal
Enemy wins	Three Xs in a row, column, or diagonal
Tie	All 9 squares filled with no winner

After the game ends, you are asked whether to play again.

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Example Session

=== CLI Tic-Tac-Toe ===
You are O. Enemy is X. You go first.

 1 | 2 | 3
---+---+---
 4 | 5 | 6
---+---+---
 7 | 8 | 9

Your move (1-9): 5
Enemy places X on square 3.

 1 | 2 | X
---+---+---
 4 | O | 6
---+---+---
 7 | 8 | 9

Your move (1-9): 1
...

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Project Structure

project-example/
├── TicTacToe.fsproj    # .NET 10 F# project file
├── run.bat             # Windows run script
├── run.sh              # Unix run script
├── README.md
├── requirements.md
└── TicTacToe/
    ├── Board.fs        # Cell type, board state, rendering, win detection
    ├── Game.fs         # Game loop, player input validation, enemy AI
    └── Program.fs      # Entry point, play-again loop

Key Types

// A cell is either an empty square (showing its number) or a placed mark
type Cell = Empty of int | O | X

// Possible outcomes of a completed game
type GameResult = PlayerWins | EnemyWins | Draw

Module Overview

Module	Responsibility
Board	Immutable board operations: create, tryPlace, winner, isFull, render
Game	Main game loop, input validation, random enemy move, end-state display
Program	Entry point; prints welcome message, drives play-again loop

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Rules Summary

• You are always O and always go first.
• The enemy is always X and always moves randomly.
• Selecting an occupied or invalid square re-prompts — the turn does not advance.
• Three marks of the same kind in any row, column, or diagonal wins the game.
• A full board with no winner is a tie.