Shameless plug, but if you are interested in Sokoban type games check out https://thinky.gg . Features a fun Sokoban variant (called Sokopath) as well as another NP hard variant called Pathology (goal is to get from point A to point B in the shortest amount of steps).

Many in the community have tried to create various solvers and things get very hard once the grid gets to be over 5x5. However, some interesting levels with very high maximum step counts have been discovered by the thinky communnity (via simulated annealing)