NoJS 3 - The dawn of Flappy Bird. Making a Flappy Bird clone using pure HTML and CSS, no JavaScript

A developer built a fully functional Flappy Bird clone using only HTML and CSS — no JavaScript whatsoever. The post explains the key techniques: using animated CSS custom properties and cubic-bezier timing for bird motion, stacked radio button labels to detect clicks and restart animations, trig-based pseudorandom pipe heights seeded by an animated variable, and pure CSS collision detection using overlapping bounding box math. The game includes a score counter via CSS counters and an end-game screen triggered by collision state.