A Roguelike RPG that is very short, based and redpilled on the source code of Shattered Pixel Dungeon, by 00-Evan.
Shorter Pixel Dungeon currently compiles for Android, iOS and Desktop platforms. It is available on GitHub.
Note that this repository does not accept PR! Forks and reports are fine.
If you'd like to work with the code, read docs somewhere else, not here.