The Hex X langauge was designed by David May. It is used by the Big Hex Machine at the University of Bristol. You can read more about the machine and langauge online:
Install via the Atom Package manager.
NOTE: The Objective C package also proivides highlighting for files with the 'x' extenstion so you may have to disable this package or manually select the correct grammar if you have both packages installed.
Please submit a pull request if you have an improvement for this package
Good catch. Let us know what about this package looks wrong to you, and we'll investigate right away.