What is the difficulty level? How is it calculated?
As the name suggests, it refers to the difficulty of clearing a stage in Shisen-Sho.
The easier stages will be easy to solve, while the more difficult ones will likely leave you in stuck. However, what determines this is a difficult question. It is not hard to imagine that human tendencies, such as optical illusions and assumptions, also greatly affect the level of difficulty. Normally, the difficulty level should be judged by a human player and based on the ” flavor” of the stage, but this is not the case with auto-generated stages.
In Simple Shisen-Sho, the difficulty of a stage is roughly defined as follows.
High Difficulty ≈ The ratio of steps that can be solved without getting stuck is low among all the combinations of steps to remove the tiles.
However, although it is called simple, it is not easy to perform the above calculation. The number of steps to remove tiles in a given stage is astronomically large, and it is impossible to list all of them with the capabilities of today’s PCs and tablets.
Therefore, Simple Shisen-Sho uses an approximate method to quickly calculate the ratio of stages that can be solved, and estimates the difficulty level. To put it simply, we solve a stage thousands of times in different steps, count the number of times it is solved and the number of times it gets stuck, and calculate the ratio. The approximate calculation of the estimated difficulty may fluctuate due to changes in computer load and other factors. In other words, the difficulty judged by PC1 and the difficulty judged by PC2 may be slightly different.
There are seven difficulty levels: Very Easy, Easy, Normal, Difficult, Very Difficult, Ultra Difficult, and Ultimate. The breakdown of each category is undisclosed, but the percentage of the stages that can be solved is almost 100% for Very Easy and close to 0% for Ultimate.
As you might imagine, there is a strong correlation between stage size and difficulty. Smaller stages tend to be easier, and larger stages tend to be more difficult. In 14×6 stege, you will rarely find a stage that is more difficult than “Ultra Difficult”; it is rare to find one in tens of thousands of stages. On the other hand, there are only a few percent of 17×8 stages that are “Very Easy”. Thus, depending on the combination of stage size and difficulty, it may take some time to find a stage with the desired difficulty level when you start playing, so you may not be able to select it.