Many games work very well when sideloaded onto the Ouya, but the unfortunate thing is that they will always show up in the MAKE section of you Ouya, away from your other games. Another rather annoying fact is that the app thumbnail may look rather poo. Luckily, there’s an easy way around these.
Step 1 - Download APK easy tool (https://forum.xda-developers.com/android/software-hacking/tool-apk-easy-tool-v1-02-windows-gui-t3333960)
Step 2 - Extract the zip file and run the executable for your machine (32 or 64 bit).
Step 3 - Add your APK using the “Select” button and then click “Decompile”
Step 4 - Click “Decompiled APK directory” and navigate to the APK folder you decompiled.
Step 4 - Edit the files you need to edit (More on that below) and then go back into APK Easy Tool.
Step 5 - Click “Recompile” and after it has finished, click "Recompiled APK directory to find your newly recompiled APK!
Changing the Android Manifest.xml so your sideloaded apps show in PLAY
Step 1 - Locate the tags
Step 2 - Add this line underneath the first intent filter tag, for example
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
<category android:name="android.intent.category.LEANBACK_LAUNCHER" />
<category android:name="tv.ouya.intent.category.GAME" />
</intent-filter>
Step 3 - repeat for any other intent filter tags (May not be necessary but some androidmanifest.xmls have one or more intent filter tags, some for advertisements etc.
Step 4 - Save the Android manifest and proceed to step 5 of the tutorial above 
Images in the Ouya Launcher
To get a nice image in the OUYA launcher, add an image file of size 732x412 into res/drawable-xhdpi/ouya_icon.png .
Amending other files in the decompiled APK
Please comment below on what you have successfully managed to change. I haven’t experimented much with this. .
