It’s the Makehuman Game skeleton, which is compatible (same bone names and structure, different joint rotations) with the Unreal skeleton. This allows the use (with minor adjustments) of the exiting animations, free and on the marketplace. We were using the MXH2 skeleton and rig to create new animations from public domain mocaps, but that is very time consuming.
We’re going to port or replace the ARPGIS demo wearable items as placeholders until we can get new clothing and armor items built.