I'm having problems with the mobile version of RAGE (RAGE HD.) I purchased the app when version 2.7 was the most up-to-date version. Every time I launch version 2.7, I get an error message, "Invalid Product ID requested. In-app purchases will not work!" Indeed, when I attempt to buy episodes 4 & 5, I can't. I even reset my iPhone to factory settings, and re-downloaded Rage HD 2.7, but the problem persisted. Recently, they released version 2.8, but when I updated to that version, the app would not even launch on my phone at all. For that reason, I deleted it and restored version 2.7 from a backup in iTunes. I’m still unable to make the in-app purchase, though. The official listing at the App Store has reviews that complain about problems with this app, so I know I'm not the only person who had been experiencing these problems.

In theory, updating to iOS 8.1 might fix the problems I've been having, but alas, iOS 6.X is the latest line of iOS that my iPhone supports. (I'm using an iPhone 3GS 32GB.) Besides, the product page at the App Store advertises that the game is compatible with iOS 6.1, so I should be able to play it on my phone.