The minimum requirements for the new version of Kingdom Rush, Frontiers, and Origins are now OS 11 and up. Devices like the iPad4 and iPhone 5C are no longer compatible.
This is because we're in the process of unifying the versions on the different platforms.
Our games been ported to what we call the "Love" engine. There are many differences with this new engine, and we try that all of them are positive. The new version has hundreds of gameplay fixes and balances. Unfortunately, this also means we had to up minimum the OS requirements.
Got any other questions?