Summary

• Press Space (or gamepad A) to throw a bouncy turtle-shell projectile that ricochets off walls, hits other cars, and is capped to 3 active shells on a 1.5 s cooldown.
• The three NPC trucks are now racing opponents (kinematic waypoint following around the outer track) instead of static props.
• Shell hits cause a dramatic Mario-Kart-style spin: target cars whirl for ~2.2 s with a vertical hop and tilt wobble; a shell ricocheting back into the player stuns the player the same way.
• Hit burst: expanding yellow ring + pooled gold emissive stars with gravity, triggered from the impact point.

Files

• js/Shell.js (new) — projectile class: small dynamic sphere, gravityFactor: 0, speed-clamped after each bounce, 6 s lifetime, 150 ms owner-ignore window. Turtle-carapace visual built from a flattened dome + hex bumps + rim + belly.
• js/NPC.js (new) — NPC class with a kinematic box body in OL_MOVING, outer-loop waypoint list, smooth heading lerp, spin/hop/tilt hit state.
• js/HitFX.js (new) — pooled ring + star burst effect.
• js/Vehicle.js — stun() method + stun-state branch in update(): locks input, spins the container, hops + tilts the body node.
• js/Controls.js — rising-edge fire input on Space / gamepad button 0, returned as input.fire.
• js/Track.js — export NPC_TRUCKS, drop the inline static-clone loop (ownership moved to NPC.js driven from main.js).
• js/main.js — wire everything: createNPCs, HitFX, shell pool, rewritten contact listener that dispatches to shells and triggers the appropriate stun/hit/burst. Bodies are destroyed outside the contact callback to avoid re-entrancy issues.

Test plan

• Serve the repo statically (python3 -m http.server) and open index.html.
• Drive with WASD; press Space — green turtle shell flies forward from the car, spinning, at a constant speed.
• Aim at a wall — shell bounces and keeps going; stays on the ground plane (no vertical hop).
• Aim at a moving NPC truck — shell disappears on contact, truck spins/hops/tilts for ~2.2 s with ring + stars, then resumes waypoint racing.
• Fire into a corner so the shell comes back — player gets stunned the same way.
• Hold Space — only one shell per 1.5 s (rising-edge input).
• Leave shells to expire — no body/mesh leaks; scene.children stabilises.
• Existing wall-collision impact audio still plays when the player hits walls.

🤖 Generated with Claude Code