APK installs only part of my game

Hello,

I am developing a game for Android and I have partially completed it (just some simple gameplay). I wanted to see how it runs on its own without the Unity Remote. So, I build the game from Unity3D and the file size is around 9mb.

I move this file onto my Android and have my phone install it (i've seen on the internet that I need some APK install app, but I can install it without such an app. I have also tried downloading an APK Installer app, but it installs my game the exact same way as without the APK Installer app). After installation, I run the game and I get the splash screen that says "Powered by Unity", then the background texture that I have in the game shows up, but there is no gameplay. Only the background displays, that's it.

I go to uninstall the game and see that it is only 128kb in size.

The Unity Remote works perfectly, but for whatever reason I can't seem to install the entire game, just the background. I don't know what the problem is. Any help will be much appreciated.

Thank you!