Dominake – A domino puzzle where 5×6 grids are impossible

Dominake = dominoes + snake. Divide a number grid into domino pairs, then link them into a continuous chain where touching ends match. Under the hood it's two classic problems at once: a Hamiltonian path covers every cell, while the domino chain forms an Eulerian path in the complete graph Kₙ. For 5×6, K₆ has all vertices of odd degree — violating the Euler condition. The grid simply can't exist. Valid sizes: 4×5 (K₅), 6×7 (K₇), 8×9 (K₉). Three difficulty levels controlled by "traps" — false matches that look right but break the chain. Chain mode gives an open snake; Loop mode closes it into an Eulerian circuit. Hold any domino to preview where it can go (green/blue/red for free/partial/blocked). Animated snake on solve. Single HTML file, no frameworks, no backend, no ads. Built with Claude as a co-pilot. https://constarik.github.io/Dominake/ More original game mechanics (slots, arcades, puzzles): https://constarik.github.io/UnclonedMath/