PLAYCRATE

Loadout has a pretty cool gore system. Sometimes you end up without a head but stay alive.

This is how it looks ingame:
http://imgur.com/IwPvo5b

There is also weapon crafting which allows you to make a lot of different weapons, but grinding is required to unlock different parts.

It’s F2P on Steam, so give it a try maybe?
http://store.steampowered.com/app/208090/