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Fourfold · Echo Stones is an independent browser adaptation of Shōbu. Game designers: Manolis Vranas and Jamie Sajdak. No publisher affiliation or endorsement.

Rules core: OpenShobu, Universal Shōbu Protocol Specifications, Apache-2.0, commit 4178b90af66d3834b465b6e9491f1f6c261c87ab. GitHub source. Observed 1 star, latest push October 11, 2026.

Changes: removed Node imports and terminal transport; added a responsive browser interface, one-ply tactical local opponent, three study endings, keyboard controls, undo and local saves. The reference rules core is retained. Blocked players lose under USP 1.0; there is no automatic repetition draw. The opponent is a modest heuristic, not a trained model.

Full Apache-2.0 license · Notices and modifications · Readable rules source · Readable application source · Source metadata