HOW TO INSTALL YGOPRO ON ANDROID

This is a guide on how to install Ygopro on Android.
System requirements

Android 3.2 - 6.0
Internal storage at least 300MB free.
~20MB for the apk, ~250MB for card images and other assets
Display at least 480x320
Download

The latest version can always be found at the download page http://www.ygopro.co/Download.aspx. The first link is the Ygopro APK file. The APK file installs the app. If you are doing a clean install (meaning you don't have an older version of Ygopro installed on your device yet) then you also need to download the Android card pics.
The card images

Ygopro is a big app. The card images take about 250MB of storage space. To avoid having to download the images for every update they are not in the stored in the main APK file, but in separate OBB files.
main.4.co.ygopro.ygoproandroid.obb
patch.44.co.ygopro.ygoproandroid.obb
The OBB files need to be placed in a specific folder on your device internal storage (SD card on older devices). The app searches for them in 2 different locations.
[Root folder]/Android/obb/co.ygopro.android/
[Root folder]/ygopro/
Connect your device to a computer via a USB cable. Browse to one of the folder locations (your choice). If the folder does not exists, then create it manually. Copying to only one of those folders is enough. You don't need to copy the OBB files to both folders. You end up with this:
/
Android/
obb/
co.ygopro.android/
main.4.co.ygopro.ygoproandroid.obb

You only need to copy the main OBB file once! Only the APK and patch obb files are needed for installing updates.
The APK file

The device needs to allow installing from a source other than the official Google Play store. This is called sideloading.

Using a file manager application (I recommend ES File Explorer), find the Ygopro APK file and tap on it. You’ll see what permissions are required, and the ‘Install’ button at the bottom.

After installing you can start the app by tapping on the duel disc icon.

Troubleshooting

The keyboard is not working.
In the Setting tab, select the Native keyboard checkbox

I cannot cancel moves! There is no right-click.
To cancel moves use multitouch: touch the screen with two fingers at the same time.

It fails to install with this error: An existing package by the same name with a conflicting signature is already installed.
Uninstall the old version of Ygopro from your device. Then install again.