Sokoban AI Solver

Sokoban is the 1980s warehouse puzzle where every box has to end up on a goal, with one wrinkle here: the keeper has to finish on a goal too, which is why each board carries one more goal than it has boxes. You can play with the arrow keys, WASD, or an on screen pad, undo a step at a time, and hand the board to a solver that animates its answer at three speeds. That solver is a plain JavaScript port of a native C++ engine the author wrote, and it returns the provably shortest solution rather than any solution that happens to work. It searches whole box pushes instead of single keeper steps, costing each push by the keeper's shortest walk to the push position plus one, and packs box positions into a 32 bit bitmask to keep states small. Everything runs in the page, with no server involved.