Weball’s Katamari Damacy level. Image: Weball (OG card), via funwithcomputervision.com.

You roll a ball across a real web page and its words, links, images and buttons stick to you. The first level is the Wikipedia article on Katamari Damacy, which is the joke and the credit in one.

The page is the playfield. Roll over a word and it peels off the page and onto the ball, and the ball grows by the area of whatever it took. Each level shows your diameter in centimetres against a goal size; reach it and the level is cleared. Clear the whole page first and you win that way instead. Images and buttons are solid obstacles until you are big enough to roll them up. Keep picking things up less than a second apart and a combo builds, with a FEVER at 25 in a row.

A pickup can also come up SHINY, a bump in rarity with double growth. Rarely, one comes up LUCKY: straight to the top tier, triple growth, and a rainbow trading-card pop-up. Those are fixed odds in the game’s code, roughly 5% and 0.6%, not something the page announces.

It plays with the mouse (the ball heads for the cursor, click to jump), with WASD or the arrow keys and space, or with a drag-stick and double-tap on a phone. After the Wikipedia level come two more: Cameron’s World, a GeoCities collage, and The Old Net. Beating any level unlocks the level select and a box that takes any URL.

Custom sites are fetched by the game’s server, laid out in a hidden frame without running the page’s scripts, then turned into a level. The page says it plainly: sites that build everything client-side come out sparse. Heavy pages are capped in height, and the fetch can fail or be rate-limited, in which case you get an error message.

It is free, with an optional Buy Me a Coffee link. It comes from Fun With Computer Vision, a small site of browser experiments and paid tutorials; its tip jar is under the name stereodrift. The idea is Namco’s: Katamari Damacy, released for the PlayStation 2 in 2004, in which a tiny prince rolls a sticky ball that picks up ever larger things.