Dino Dots 1.0.0 is on the Chrome Web Store — Dots and Boxes against a dinosaur AI that plays real chain strategy. See the project page.
The game underneath
Dots and Boxes looks like a children’s game and is not one. Two players take turns drawing a single line between adjacent dots on a grid. Complete the fourth side of a box and you claim it — and you move again. That one rule, the free extra turn, is what turns a doodle into a game with real theory behind it.
The beginner’s instinct is to take every box available. That instinct loses. Once the board fills in, the position resolves into a set of long chains, and whoever is forced to open the first chain hands the entire thing to their opponent, who claims every box in it and then moves again.
Why a dinosaur that plays chains is hard to beat
The T-Rex plays for the chain structure rather than the immediate box. It will decline free squares to avoid being the one who opens a chain, and it counts the parity of the board — whether the number of chains works out in its favour — before it commits.
The counter, once you see it, is the double-cross: instead of eating an entire chain, you take all but the last two boxes and deliberately hand those two back. You give up two squares to force your opponent to open the next chain. Against the dinosaur, that is usually the difference between losing narrowly and winning.
Where to play it
Dino Dots runs as a Chrome side-panel extension, and there is a full browser version on the site if you would rather not install anything: play Dino Dots here.