If your screen won't rotate from portrait to landscape orientation on Android, the most likely explanation is that you've got auto-rotate turned off.

Android’s split-screen mode lets you put two apps ... goldfish builds are intended to run in the Android Studio ... display resolution will be 2,076 x 2,152 in its default portrait orientation.

Android application developers can disable auto-rotation and lock the orientation of the screen for their applications, which is often done with games that are designed to be played on a landscape ...

Android (4.0+): Some apps work better in portrait mode, and others work better in landscape. Swivel lets you set a permanent orientation for any app o ...