You are a senior game-engine engineer. Create a complete, hi...

Prompt

You are a senior game-engine engineer. Create a complete, highly polished, genuinely playable open-world city simulation as ONE self-contained index.html file. This is a one-shot implementation challenge. Do not provide explanations, plans, pseudocode, placeholders, TODOs, abbreviated sections, or descriptions of features that are not actually implemented. Return only the complete executable HTML document in one code block. TECHNICAL CONSTRAINTS * Exactly one HTML file. * Inline HTML, CSS, and JavaScript only. * No external libraries. * No external images, audio, fonts, APIs, or assets. * All graphics must be procedurally rendered with HTML5 Canvas and/or inline SVG. * All sound effects, if implemented, must be synthesized with Web Audio. * It must work by saving the response as index.html and opening it directly in a modern desktop browser. * Target smooth 60 FPS gameplay. * Do not deliberately simplify the specification because of its size. Implement as much depth as possible and prioritize complete working systems over explanatory prose. * Do not replace requested systems with static visual approximations. WORLD Create a large scrolling city substantially larger than the viewport. The city must contain: * interconnected multi-lane roads; * intersections and traffic lanes; * sidewalks; * varied building blocks; * alleys; * parks and green spaces; * water or another major environmental landmark; * street lights and road markings; * procedurally varied decorative objects. Generate the city deterministically from a fixed seed so refreshing the page produces the same layout. Implement a smoothly interpolated camera following the player. PLAYER The player begins on foot. Implement: * WASD and arrow-key movement; * directional facing; * walking and running; * collision with solid buildings and world boundaries; * health; * melee attack; * ranged attack with finite ammunition; * hit reactions; * death and respawn. The player must visibly animate through procedural shapes rather than being represented only by a plain circle or rectangle. VEHICLES Populate the city with multiple visually distinct vehicle classes. Implement: * parked vehicles; * vehicles actively driving through the road network; * acceleration and braking; * reverse; * steering dependent on forward speed; * momentum; * drag; * collisions; * vehicle health; * entering and exiting vehicles; * hijacking occupied vehicles; * visible damage feedback. The player enters or exits the nearest valid vehicle with F or Enter. NPC AND TRAFFIC AI Create a population of pedestrians with autonomous behavior. Pedestrians should: * walk along sidewalks; * choose destinations; * avoid obvious obstacles; * react to nearby violence; * flee dangerous vehicles; * be damageable; * eventually respawn elsewhere to maintain population. Traffic vehicles should attempt to: * follow roads and lanes; * turn at intersections; * avoid obvious collisions; * react to blocked traffic. WANTED AND POLICE SYSTEM Implement a wanted level from zero to five. Crimes such as attacking civilians, firing weapons near civilians, hijacking cars, and harming police increase wanted pressure. Wanted pressure should decay when the player escapes police attention. Police must: * spawn intelligently away from the player’s immediate view; * use police vehicles; * navigate approximately toward the player using the street layout; * leave vehicles when useful; * pursue on foot; * attack or attempt arrest; * search around the player’s last known position after losing sight. Higher wanted levels must measurably increase police aggression and response. GAMEPLAY SYSTEMS Implement at least three different repeatable mission/activity types, for example: * delivery or taxi; * checkpoint race; * vehicle theft; * pursuit escape; * target elimination; * package collection. Create an economy with money rewards and meaningful things to purchase, such as health, ammunition, repairs, or upgrades. Add pickups or interactive world locations. UI Create a polished game HUD containing: * health; * ammunition; * money; * wanted stars; * current vehicle condition when driving; * active mission information. Add a real-time minimap showing: * nearby roads; * the player; * relevant vehicles; * police; * mission targets. Create: * title screen; * pause menu; * controls/help panel; * game-over state; * restart flow. VISUAL QUALITY Aim for a distinctive late-1990s / early-2000s top-down arcade aesthetic without copying assets from any existing game. Use: * shadows; * varied architecture; * procedural vehicle details; * animated water or environmental elements; * particles; * skid marks; * muzzle flashes; * explosions; * screen shake; * day/night or atmospheric lighting variation if feasible. ENGINEERING QUALITY Organize the JavaScript into coherent systems/classes rather than a single monolithic loop. Use delta-time animation. Prevent unbounded accumulation of particles, bullets, NPCs, or event handlers. Handle browser resize correctly. Avoid obvious console errors. Include a deterministic seeded pseudo-random generator where procedural generation requires randomness. FINAL REQUIREMENT This is intended to test how much complete, interconnected software an AI can produce in a single response. Do not merely satisfy the visual appearance of the features. Make the systems interactive and connected to each other. Spend the available output budget on implementation rather than explanation. Do not omit later sections simply to keep the answer short. Return ONLY the complete index.html source code.

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