Kobold Shisen is an interesting variation on Mahjong Solitaire. The aim of the puzzle is to remove all the tiles from the grid.

The rules are simple. Remove matching pairs of tiles where a matched pair has the same face and can be connected by three or fewer lines. The lines cannot pass over another tile but can extend beyond the border of the grid.

There are nearly endless puzzles available and all are at least theoretically solvable.