Should I make a full rig for a FPS?

I am making a First Person Shooter, so I made only the hands of the player in Maya but, should I make the full rig or only the arm bones? What influence does it have for the gameplay?

 

If you only have hands, you won't be able to pull the camera back into a third person view. But third person adds a whole extra layer of complexity, not just the model. Unless you really need to do third person, I don't see a need for anything except arms, unless you also want to build enough of the body so the first person character can look down and see his legs.

 

In my experience. We have had full characters for the FPS player character.

Because you may want some cutscene moments or scenes in game where the character needs to get up after falling down.

Plus you need to project a shadow.

 

The shadows are a good point. For cutscenes, you may want to instantiate a model only when needed, or even different LODs or models depending on whether the cutscene is a closeup or further back involving multiple characters.

 

What about the rig?Can I make the character move naturally without it? Maybe only the legs?
Can I project the shadow having only the hands(either in Maya or Unity).

 

In first person, the camera rig will move differently than in third person. Typically in first person the camera bobs a little to simulate head movement, and this is independent of any model rigs. In third person the camera is smooth but the third person model may bob a bit as it walks.

Shadow projection depends on how much detail you need. If you're only doing blob shadows, you don't need a body. If you do need a body, it doesn't have to be details -- just very simple arms and legs. Always use the least detail necessary to achieve the required effect. This leaves more CPU and GPU for other visual effect and things like AI.