Okay, this is what Descent sounds pretty much close to.
You can use the G string to be the guitar riffs if you use --4-0--
after each riff.
The strings go from top to bottom (E to G):
Intro: (let all riffs ring out a bit)
---0------2---------4---------5-------------0-------2------0- (let ring out)
-------------------------------------------------------------
-------------------------------------------------------------
----4-0-------4-0-------4-0------0-4-0---------4-0----4-0----
Second part
---0-----2-------4-------5---------0------2--------0-4-0-4-0-4-0-4-0-0-
-----------------------------------------------------------------------
-----------------------------------------------------------------------
-----4-0----4-0-----4-0----0-4-0------4-0----4-0-----------------------
repeat intro for preverse...
Verse:
---0--00-2--2--2-0--0-00-2-0-2-0-------------------------
---------------------------------------------------------
---------------------------------------------------------
---------------------------------------------------------
[ Tab from: https://www.guitartabs.cc/tabs/f/fear_factory/descent_btab_ver_2.html ]
pre-Chorus:
---0-4-0-4-0-4-0-4-0-0----------------------------
--------------------------------------------------
--------------------------------------------------
--------------------------------------------------
Chorus: (repeat about six times)
--0------2------4------5---------6----------------
--------------------------------------------------
--------------------------------------------------
----4-0-----4-0---4-0------4-0------0-00-4-0------
Rest:
---555--3-0-0-0-222--2-2-2-2--4-44-4-0-3-3-5-5--2-2-2-------
------------------------------------------------------------
------------------------------------------------------------
------------------------------------------------------------
then repeat the da, da, da, da stuff with the intro.
Ending:
---0-----2-----4-----5-(after 3, do this:)-555--3--5-0-(let ring out)
-------------------------------------------------------
-------------------------------------------------------
------4-0--4-0---4-0---4-5-4---------------------------
That's all, I hope you like it. I know that the song structure is a bit
misleading, but what I have down are the basic bass riffs for ya.
Thanks.