If you like challenging games, this is absolutely the right game for you to try.
When a tile is surrounded by larger tiles, the tile is removable. When a tile is removed, you get scores of subtraction from all smaller numbers.
For example, if 5 is surrounded by 6-7-8-9, 5 is removable. When 5 is removed, you get scores of subtraction from tiles of 1 to 4, or 10 points.
Scores for each removable tile will be displayed at the first move.
You can try as many times as you wish to achieve the highest scores. You can also choose to view the correct answer.