Left is a free and open source distraction-free text editor for Linux, Windows and Mac.
The main goal of Left is to get you to focus on writing. It comes with writing essentials like autocomplete, synonym suggestions and writing statistics, but it doesn't support text formatting, and doesn't have all the bells and whistles found in applications like LibreOffice Writer or Microsoft Office Word.
This minimalist text editor may not be particularly exciting, and it's not for everyone, but if you're working on a long writing project, a clean interface that allows you to focus exclusively on your work may be for you.