Gears is in public Beta. Download the installer for the current build, and execute. You need a Windows machine with at least OpenGL 3.4. GEARS has been tested for nVidia cards, there are known issues with integrated Intel chipsets.
Gears source code is available on GitHub.
Editable Python sripts (under LGPL licence) are now installed in AppData, thus avoiding file access problems if Gears is installed in Program Files.