Just curious does this statement affect Gems of War?
3.1.1 In-App Purchase:
If you want to unlock features or functionality within your app, (by way of example: subscriptions, in-game currencies, game levels, access to premium content, or unlocking a full version), you must use in-app purchase. Apps may use in-app purchase currencies to enable customers to “tip” digital content providers in the app. Apps and their metadata may not include buttons, external links, or other calls to action that direct customers to purchasing mechanisms other than in-app purchase.
Any credits or in-game currencies purchased via in-app purchase may not expire, and you should make sure you have a restore mechanism for any restorable in-app purchases.
Remember to assign the correct purchasability type or your app will be rejected.
Apps should not directly or indirectly enable gifting of in-app purchase content, features, or consumable items to others.
Apps distributed via the Mac App Store may host plug-ins or extensions that are enabled with mechanisms other than the App Store.
Apps offering “loot boxes” or other mechanisms that provide randomized virtual items for purchase must disclose the odds of receiving each type of item to customers prior to purchase.