Hi all! I just published the 0.1.0 release of Mill:
Mill is a new build tool that can serve as a replacement for SBT. It aims to be fast, simple, and friendly.
The linked docs give an introduction to Mill, what it is and how to use it. There are example builds for a bunch of open source projects linked from the documentation (Acyclic, Ammonite, Better-Files, Jawn, Upickle) so you can see how Mill is used in real situations to build real code.
Mill is under active development, but is already very usable and can be used as a substitute for SBT in many real projects. If you are interested in trying out a new build tool, give Mill a shot!