Blenrig 6
Can I add extra limbs?
Not automatically, BlenRig currently doesn't have a modular workflow.
Is it compatible with Game Engines?
Not by default, but there are plans for that.
Is BlenRig only for Bipeds?
Yes, for now it is.
The Guide is not showing, what can I do?
Make sure you have the "Show Gizmo" overlay option enabled
The Guide is behaving weirdly on Mac
Yes, on Mac the guide skips steps and does weird stuff. Most presumably because of some OpenGL issue.
Once the BlenRig Guide is ported to the newer OpenGL libraries of Blender 3.6, Mac should work ok with the guide (cross fingers)