Quantum Breakout

   

A quantum version of the classic Breakout game. Your paddle is a quantum state: you build a small quantum circuit to control where the paddle can be, then break the bricks. The paddle's opacity over each position is the probability of measuring that state; as the ball approaches, the state is measured and the paddle collapses to a single position.

Built with Pygame on top of the reusable qcge (Quantum Circuit Game Engine). The circuit runs on real Qiskit on the desktop and on a dependency-free pure-Python statevector simulator in the browser (pygbag/WebAssembly), where Qiskit cannot run - so the exact same game plays both places.

Learn by playing - in-game levels

There is no separate tutorial to read: the game teaches itself. Each level opens with a short concept board, then restricts the gate palette so you practise that one idea:

1. Superposition - the H (Hadamard) gate spreads the paddle across positions.
2. Measurement & Collapse - the approaching ball measures the paddle to one position.
3. Pauli-X (bit flip) - X moves which basis state you occupy; combine with H.
4. Phase: Z, S, T - phase is invisible to a single measurement but changes interference.
5. Entanglement (CX) - a controlled-X links two qubits.

Play instructions

• Arrow keys - move the circuit cursor.
• X / Y / Z / H - place an X / Y / Z / Hadamard gate.
• S / T - place S / T phase gates. (This is why the cursor uses the arrow keys, not WASD - the S key is needed for the S gate.)
• C - make a gate controlled, then R / F to attach the control above/below.
• Q / E - turn X/Y/Z into a rotation (RX/RY/RZ), decreasing/increasing the angle by π/8.
• Backspace - remove the gate under the cursor. Delete - clear the circuit.
• Space - advance the concept boards / start a level.

Run on the desktop

python -m venv qenv
# Windows:  .\qenv\Scripts\Activate.ps1     Linux/macOS: source qenv/bin/activate
pip install -r requirements-dev.txt
python main.py

On the desktop qcge selects the real Qiskit backend automatically.

Build for the browser (itch.io)

The browser build is produced with pygbag and must stay numpy-free (importing numpy inside pygbag breaks the SDL display); qcge's backend="auto" handles this by using its pure-Python simulator in the browser. Full, reproducible steps - including the post-build theming - are in WEB_BUILD.md.

Credits

A quantum re-imagining of the Atari Breakout, inspired by and indebted to QPong by Junye Huang and the Qiskit 12 Days of Qiskit series (playlist). Originally built for Team Abraxas at Fest Nimbus (NIT Hamirpur), and rebuilt for v2 on the standalone qcge engine with in-game teaching levels and a browser build.