Made it beginner-friendly

Setup screen now shows just the 4 controls that matter; the other 14 physics params are tucked into a collapsible Advanced section.
Added one-click “recommended settings” (auto-applied per level), an onboarding banner, a “How to play” panel, a Simple/Detailed toggle on the play screen, and a coaching tip on the results screen.
Made the simulation more physical

Upgraded the controller from P to full PID (added Damping/Kd and Integral/Ki).
Switched to analog reflectance sensors (smooth weighted line position instead of on/off).
Mass now affects acceleration, and cornering too fast causes a real outward skid.
Added fun/juice

Sound effects + mute toggle, a 3-2-1 countdown, win confetti, a reactive robot face, slip sparks, milestone toasts, and a glowing trail.
Repo

Added a full README, .gitignore, and pushed everything to GitHub (kept the existing MIT license and history).