I did some research and found that Quake 3 split their models into 3 pieces: the legs, torso, and head. They positioned each one in the "correct" location using "tags" in engine. They then independently bent the torso and head forwards or backwards depending upon if the player looked up or down.
This was a long time ago, when 3D rigs where simple things.
You could still do it this way, however you will have lots of limits on what you can achieve with such a simple rig. The advantage would be the performance you can get from it.
Search "3D character animation" "3D rigs for game animation"
http://iamzimmer.blogspot.co.za/2013/01/game-character-rig-skeleton.html
This is a example of a more modern rig I found on the net, one of the first images Google provided.
This appears to be a complex all purpose rig, before exporting the helper bones would have to be deleted.
In general most rigs have 42 bones on export.
Note: This is for the most used rigs(humanoid enemies in shooter games) and after exports, the rigs used to create the animations is as large as the animator needs.
Head, Neck, Eye guide, Cervical, Thoracic, Lumbar, R/L Arm, R/L ForeArm, R/L Hand, Pelvis, R/L UpperLeg, R/L LowerLeg, R/L Foot, R/L Toes.
The Hands are: Palm, Thumb(3 joints), Index Finger(3 joints), MiddleFinger(2 joints) and the RingFinger and Pinky both share one bone.
I have seen some developers creating bones for each finger with 3 joints each, that is 15 bones for one hand, combined with the toes you would need over a 100 bones for such a complex rig.
The other downside is that each bone, if they are animated or not, will have a impact on performance. So using a 15 bone hand on a character that only has to pull a trigger is just a waste.