Using MIT’s App Inventor, you can write apps for your device!
A short video explaining how to install an apk file on your device is here
The Master Game Pack
SIX GAMES IN ONE!
I use this as a project in my Exploring Computer Science class to teach a database, timers, counters, and objects.
The apk file is here
The explainer video is here
Talk Helper
A communication aid for non-verbal folks.
The apk file is here
The explainer video is here