Recently, Titan Empires had a semi-major update from version 5.1 to 6.0 and many people are receiving an error "Game content can't be found" or something very similar to that. This update wasn't normal because instead of replacing the old app like usual it had you install a whole new apk file and had 2 installations on the device.
Ok, whatever, not a big deal as you can just uninstall the old version and it still seem to run fine on my 10.5 inch Tab S. When I tried installing on any other device (both rooted and not) I received the aforementioned error. After a few hours (off and on) of uninstalling/reinstalling everything and cleaning all leftover traces nothing seemed to work. I then had an idea to try reinstalling the old version again and repeating the update process and it worked! I then repeated these steps on two more devices that had the error and they worked as well! I then uninstalled the old 5.1 version and 6.0 still works on all devices!
Steps to fix error:
Completely uninstall any traces of Titan Empires (if rooted you can look for left overs with something like SD Maid etc.).