looking for help with base rigging a game model i am looking for help trying to set up a custom made skeleton for a game unit (For xcom 2) that i have made the concept sculpt for, but my skills with setting up something like that are more or less non existing as i am very new to stuff like this.
I have done custom animations before / edited existing animations and i know how to add custom / more bones to existing skeletons

examples of some of my animations here
https://streamable.com/khmug
https://streamable.com/jpcw0

so i am thinking I got this part down (somewhat)

the model i sculpted is here
https://imgur.com/a/RnOJq

i have tried on and off for a few months trying to set up a rig for this but have to admit i actually dont have the skill to do that yet.. 

anyone in here that would be able to provide some guidance on how you would set this up for animations?
It looks like you might need to start with some re-topology or a decimation modifier first. Lower the poly count so the engine can cope with your model, if it's not for a rendered cut scene that is.  
Next Add some bones, the first bone must be created in
object mode (Tab), add a armature bone (Shift + A, A, S).  

To keep the bones visible in front of your mesh, select a bone then go to the
Properties panel, Object Data tab, Display drop menu, TICK In Front.  

In edit mode: Extrude bones (E), Parent bones (Ctrl + P), Clear Parent Bones (Alt + P) 
or
add bones (Shift + A).  
Parent the object (mesh) to the armature (Bones): Select the object, and the armature together 
(Shift + LMB) and parent them with automatic weights (Ctrl + P, I).