Clause 2.25 was introduced in Apple’s App Store Review Guidelines that will effectively render Kakaotalk gaming services unusable.
Apparently aimed at app-promotion services that compete or divert the central experience out of Apple's hands, this clause was included to protect the integrity of App Store product rankings. Apple is trying to enforce the use of Apple's GameStore to provide 'equal opportunities for app developers' but it remains to be seen how app developers will be affected by this. This myopic clause will mean that iPhone users will not be able to play popular games such as ‘AniPang’and ‘Viking Island’. Kakaotalk is currently awaiting an official announcement from Apple as of yet.