The Lifeline series was a very popular horror adventure game. However, the reason why the game had disappeared from the app Store was still unclear. If you are interested in the game, you can try to find it on other online game platforms such as Steam, GOG, etc. You can also use a browser plug-in or search engine to find the game's version on iOS. It was important to note that Apple often updated and deleted the content on the App Store, so it was common for games to disappear. If you still can't find the Lifeline series, try checking the update history of the Apple App Store or contact Apple's customer support for more help.