If you're looking for the theme, click here: Halloween (Theme) Edit
Level 11: Halloween, was the first themed level. It was also the first level to include a name in the level select screen, but not the first overall. The level can be unlocked by obtaining 3 keys. CheetahMobile decided not to realease the level for the Arabic Rolling Sky as the vast majority of natively Arabic-speaking people do not celebrate Halloween. However, any Arabic-speaking player that wishes to play the level still can, by switching the language in the Rolling Sky settings.