ApexCtl
https://github.com/tuxmark5/ApexCtl

Why should this be included in the repository?
Adds support for the Steelseries Apex and Apex [RAW] keyboards. Without this the extra keys are not usable (they do nothing).

Is it Open Source?
Yes

How many users do you anticipate will use this software?
No idea.

Link to source tarball/zip file
https://github.com/tuxmark5/ApexCtl/archive/v0.0.1.tar.gz