Platform: Tested in Windows XP - 10. Since it's written in bash, should run in Linux/Unix.
Features:
Completely portable on Windows (all needed unix tools, node, lessc, a bash shell included)
A simple CLI API, with only a few commands, trying to keep it simple
MarkDown for the content
Pandoc as MarkDown to HTML conversion engine, using pandoc's HTML5 template, or a custom template
Custom Header/Footer
LESS support
In linux/unix, you should need only the main script (marksite.sh), and off course pandoc, and node and lessc (if you wanna use LESS for your stylesheets)
(Re)generation of changed/added pages/stylesheets/other only, not the whole website