About onlymove.net

This project was created by Henry Hemming and started on July 12th, 2025.

Problem Details

How accurate are the ratings?

The rating model is checked against players' self-declared ranks on other servers. It is also validated on held-out problems it never trains on, and the check is repeated over several independent runs — each retraining the model from scratch with a different randomly drawn 10% of problems set aside — to confirm it generalizes to unseen positions rather than memorizing, and that the result does not hinge on any one lucky split.

Both figures rest on a few hundred self-declarations, so each carries the sampling margin shown. A difference smaller than that between one refit and the next is noise, not movement.

The full technical account — how the ratings, the ranks and the weakness dimensions are built, and how the app uses them — is in the methodology.

Why train this way?

Fitting difficulty to real human results, targeting an ~80% success rate, and reviewing at a constant recall probability are not arbitrary choices — each rests on findings from the learning-science literature.

Ranking System

Features

Changelog

See the full changelog for the complete history of updates.