Add a Coin Flip game #1

Context

The arcade has four games. Adding a fifth is the easiest way to contribute here,
because you write a brand new file instead of working out how someone else's code
fits together. Nothing you write can break an existing game.

What to change

Create: arcade/games/coinflip.py
Edit: arcade/main.py — add your module to the import line and to the GAMES list

The game: the player calls heads or tails, three times in a row. Get one wrong
and the round ends.

Your file needs exactly three things:

• NAME — the title shown in the menu
• DESCRIPTION — one line under the title
• play() — runs the game and returns a score (higher is better, 0 for a loss)

docs/how-to-add-a-game.md contains a complete
working Coin Flip you can copy and adapt. Use it.

Acceptance criteria

• arcade/games/coinflip.py exists with NAME, DESCRIPTION, and play()
• The game appears in the menu when you run python3 -m arcade
• It is playable start to finish, both winning and losing
• It uses ask_choice from arcade.input_utils, not bare input()
• It uses arcade.art for colour, not raw escape codes
• tests/test_coinflip.py exists with at least one test
• python3 -m pytest passes

How to verify locally

python3 -m arcade        # play it, win and lose
python3 -m pytest        # all green

Difficulty

Beginner. No prior knowledge of the codebase needed.

New here? Comment /claim on this issue and a bot will assign it to you. Then read CONTRIBUTING.md.

Stuck at any point? Comment here saying what you have tried, or come to a PR Debug Clinic (Oct 12 or Oct 21). Getting stuck is the normal experience of learning this, not a sign you are doing it wrong.