FocusWriter lets you personalize your writing environment with customizable themes. The rest of the app vanishes when you need it to, and you're left alone with the page, and the background of your choice. The design is the bare bones kind of minimalist instead of the Scandinavian design kind (like OmmWriter), though. The result of this approach is a lack of features compared to other text editors. For instance, there is no in-app file-tracking system, so you'll have to keep your files well-organized in your file system.
The app makes up for it with things like timers and alarms (for all you pomodoroheads out there), as well as a calendar to track your progress (how's that for bare bones), portable mode and other welcome surprises.
Notably, FocusWriter is the only app featured in this list to have a Linux version.
Very bare bones
No in-app file tracking
No cloud support