Space Invaders · mistral-nemo

Build a playable Space Invaders-style game on a canvas using procedural graphics. Use HTML, CSS, and JavaScript as needed. Write it to `index.html` in the current working directory using your file tools. Inline your own CSS and JavaScript. Do not use external assets, CDNs, or network requests. No third-party libraries are provided. Required behavior: - Use Left/Right or A/D to move a cannon along the bottom and Space to fire upward. Display the controls and keep the cannon within the playfield. - Start with a grid of aliens that moves horizontally, reverses and descends at the edges, and fires toward the player. Player shots remove hit aliens and increase score once. - Place destructible bunkers between the cannon and aliens. Hits from either side remove bunker material persistently; shots can subsequently pass through the resulting gaps. - Start with three lives. Enemy shots cost a life with brief protection from repeated damage. Aliens reaching the player zone or zero lives causes Game Over; clearing the aliens shows a win state. - Provide Restart to restore aliens, bunkers, score, lives, and player position. Bound projectile lifetime and fire rate. Verify: Test movement and firing during the opening formation. Check alien motion and inspect a shot hitting a bunker or alien for visible damage or score feedback. Use Restart and check the initial formation, bunkers, lives, and score.