Endless Graeco-Latin Squares

A Graeco-Latin square is two Latin squares laid over each other so that every pair turns up exactly once. The name comes from Euler, who wrote one square in Latin letters and the other in Greek. This page makes endless puzzles of them. It started as an unofficial endless version of Tupo by Josh Collinsworth, which is built on the same idea. Fill a 4×4 or 5×5 board so each row and column holds every number and every color once, and every number + color pair appears once on the board. A ledger tracks which pairs are placed, and each difficulty level needs one more kind of check. Hint describes the next deduction and highlights the tiles it relies on.

Last updated 2026-10-15 04:15 UTC · made on claude.ai

Model, effort and cost weren't recorded for this one: it was made on claude.ai, which doesn't keep them with the page.