Fixed minor bugs,Correction of difficulty level

・Fixed minor bugs
・Correction of difficulty level
・When returning to the title on the game over screen, a confirmation screen is displayed.
・A checkpoint has been added in Area 6-1. Adjustment of difficulty level.
・Adjustment of difficulty level in Area1-3.
・Some enemy settings have been changed.
・Fixed flickering when the pause screen is first opened.
・Other minor bug fixes.