What is Game Inject?
Game Inject is a third-party app store that hosts the best and useful apps and tweaks that are not available on the App Store. If your app is listed here and you'd like to have it removed, then please send us a Direct Message on Twitter.
I get "Untrusted developer" popup when I tap to open an app.
After installing an app, you have to verify its profile from Settings. To do so, go to Settings > General > Profiles & Device Management, then tap on the profile name and choose "Verify".