Fixed a recent bug that prevented players from reaching level 4

-Optimization of shadows in level 4

-At present, if the fps are less than 50 fps on the title screen, the game goes into medium quality, and if the fps are less than 30 fps, the game goes into low quality. If the computer had trouble starting and the fps were low from the start, and the fps become high again, the game can return to a high number of fps

-Adjustment of a recent bug that prevented going to level 4