Zig Zag Arithmetic Line

Open Zig Zag Arithmetic Line and you are playing — a Puzzle game that runs on the page rather than beside it. Taps and swipes are the whole vocabulary — a phone plays it best. Catalogued as arcade, educational, game, math, online.

It is drawn for a tall screen, so it fills a phone held upright rather than a wide monitor. Free to play in the browser, with no install step between you and the first round.