Cyborg (contracted from Cybernetic Organism) is a term used to describe a being that combines living tissue with a significant quantity of machine parts. How much machine is up for debate - describing someone with a pacemaker or artificial leg as a cyborg is liable to invite mockery (and not of them), wheras the "full body cyborg" (consisting, essentially, of an android with a wetware processor) appears to be an established science fiction convention. In between the two extremes are various wetware fit-outs of varying credibility. Cyberpunk is particularly fond of this sort of thing.
For those cyborgs which consist of a promiscuous mix of living tissue and metal, very little thought is typically given to the sort of required secondary powers needed to install the machine parts - to achieve super lifting strength, for example, it would probably be necessary to replace (or at least massive reinforce) pretty much the entire skeleton. Likewise, implanted weapons should be subject to a stringent sanity check and the measures needed to keep the "meat" parts healthy and functional need to be considered1.
Game and Story Use
- Cybernetic parts as a cool thing is fairly standard stuff, even if most settings that use them try to mix in a bit of angst - usually with a mechanism designed to imply that having implants drives you insane. The idea of a wetware fitout being involuntary or undesirable could be something of a subversion - perhaps because the majority of cyborgs are discharged veterans from an unpopular war, or modification is common amongst indentured labourers or criminals. Discrimination against cyborgs and genuine side effects to be an expected feature.
- What makes for a genuine side effect will depend on your system and setting - social rejection and the requirement to live on protein items may be a big thing in a roleplaying-heavy setting, but in one focused around combat they're pretty much free points and you'll need to choose something the players will notice. If nothing else, the requirement for expensive anti-rejection drugs might help.
- Arguably some degree of mental illness might be a pre-requisite for voluntary modification rather than a result - someone horribly mutliated and rebuilt might be traumatised as a result, but it would take a somewhat diseased mind to remove healthy, functional organs and replace them with dead metal.
- Whole body cyborgs may actually be a lot more practical than partial builds - either the robot with wetware processor or the "meat doll" which reverses the process and has a living body with the key functions of the brain replaced by computer parts to allow an AI or other electronic mind to use it.