XRevert is previously known as YosemiteRevert.
XRevert (was YosemiteRevert) changes application icons, system icons (such as the folder icon), menu bar icons, and more, as well as the system font, in OS X 10.10 Yosemite and later back to the way they were in prior versions of OS X. It also makes changes to aesthetics, such as the "traffic light icons" and menu textures.