The object of Shanghai® II is to clear the board by removing pairs of matching TILES. The obstacle is that only unblocked TILES can be removed. A Tile is blocked if there are TILES touching both its left and right sides, or resting on its upper surface. If a Tile can slide to the left or right without disturbing another Tile, it is unblocked and free to move. Adjacent TILES positioned higher or lower on the screen do not have a blocking effect.

Some Tile sets contain special groups of TILES. A Tile in a special group matches any other Tile in its group, even if the TILES are not identical. For instance, the MAH-JONGG Tile set contains four seasons TILES (SPR, SUM, AUT, WIN) that match each other. In the PAIRS Tile set, there are four special groups that consist of two pairs of TILES. Each pair is made up of two identical TILES that directly oppose the other two in the group. For example: with the Fire and Ice TILES, match a Fire Tile to another Fire Tile or to an Ice Tile.