Kero is a largely black-box implementation of Valve’s source engine, written using Go and OpenGL
What is it?
Kero is an implementation of a BSP viewer with physics support, born from another project of mine Lambda-Client. It’s very much a Work-In-Progress, and likely will remain that way forever more given the scope of the project; however right now it can be used to load Counterstrike: Source, Half Life: 2, and Counterstrike: Global Offensive maps and view them.
It supports rendering of brushes, displacements, lightmaps, static and dynamic props, as well as Physics courtesy of Bullet Physics.
I add blog posts from time to time sharing a few updates, although the project moves very slowly. Check them out!
Screenshots

You can find Kero here: http://github.com/galaco/kero