This is the core binary of Alacrity, which runs CEF itself. This is run by Unity whenever the game launches so that it works seamlessly in the editor and in play mode. It simply receives keyboard, mouse, and other events via an IPC pipe and forwards those to the CEF browser. It also forwards back to Unity the CEF browser render information like the shared texture handle.
You'll need to have purchased Alacrity in order to build this. It's expected that this resides next to your Assets folder inside of a Unity project, and the Assets folder has Alacrity at the root.
./build.sh
Building it should produce the Alacrity.mv file (which is a .exe binary renamed) in your Assets/Alacrity/AlacrityCore folder.