The latest update includes two new game modes, Shisen-sho and Shisen-sho gravity. They have slightly different rules from classic 3d mahjong solitaire:

• All tiles are arranged in a 2d plane, not 3d.
• Two tiles can be eliminated if they match, and they can be connected by 3 straight (horizontal or vertical) lines that do not pass through any other tiles.

In gravity mode, the tiles will additionally fall down to occupy space from eliminated tiles, meaning that some combinations become harder to make

As with normal modes, the game guarantees that all puzzles are solvable.