Tic-Tac-Toe in Python

You

Computer

Draws

⌨️ Controls

← → ↑ ↓ move the dashed cursor
Space or Enter play there
Clicking or tapping a square works too
R next round • P pause
🎮 Xbox controller? Just plug it in or pair it — the stick and D-pad are the arrow keys, A is SPACE, Menu pauses and View starts again

🎯 How to play

You are X and you always go first.
Get three in a row — across, down or diagonally.
The computer replies straight away, so every tap is a whole turn.
The scoreboard keeps count across rounds.

🤖 How the computer thinks

1. If it can win this turn, it wins.
2. If you are about to win, it blocks you.
3. Otherwise it takes the middle — that square is on four lines.
4. Otherwise a corner, which is on three.
Those four rules are enough that it never loses. A draw is a win for you!

🧑‍💻 This whole game is Python

There is almost no JavaScript on this page. The browser downloaded Pyodide — a complete Python interpreter compiled to WebAssembly — and then ran the .py files in funtime/pylib/. Python does the rules, the maths and the drawing.

File	What it does	Good functions to try re-writing
pylib/tictactoe_rules.py	The rules, and the computer's brain	`winning_line`, `is_draw`, `computer_move`
pylib/tictactoe_draw.py	Painting the board — Python calling the canvas	`draw_mark`, `draw_winning_line`, `square_at_pixel`
pylib/tictactoe_web.py	The glue: clicks, keyboard, the scoreboard	`do_action`, `on_board_click`, `start_game`

🔍 Compare the two versions. Open lib/tictactoe-rules.js and pylib/tictactoe_rules.py side by side — same ideas, two languages.

🛠️ Build it yourself: Build Tic-Tac-Toe in Python walks you through the functions one at a time.

⚠️ If the game never starts: the page has to read its .py files, which a browser will not do for a page opened straight off your disk. Use the live site, or run python3 -m http.server in the project folder.