In some settings, particularly cyberpunk, you can treat an organic brain as a sort of processor. It's the hardware (or wetware, of you like) that runs the "mind" software which gives a person a personality and memories.

If you accept this premise, it opens up all sorts of intriguing gaming possibilities. Think of anything you can do with a computer, and apply it to a brain. You could download and copy the software, and run it on a different machine, thereby making intelligent software clones of someone's personality. You could upload stuff to it: upgrades and enhancements, additional capabilities and skills, or... viruses and malware. Someone could hack your brain and install surveillance code without you knowing.

Or someone could change the software, thereby changing your personality... or your memories. You'd be absolutely convinced that something happened in your past, and have vivid memories of it - all implanted like in Total Recall.

One simple premise, so much promise.

Transcript

GM: Corey, make a Will save at minus 10.
Luke: Yikes. 12... not good enough with that modifier.
Anakin: {possessing Luke} Noooo!!! You won't betray me again! Any of you!
[SFX]: Whooom! {attacks Vader}
Darth Vader: Anakin! Stop!
Anakin: I'll kill you! You never loved me! You just wanted my power!
[SFX]: Whooom!
[SFX]: kzzrzzkk!
[SFX]: Whooom!
[SFX]: kzzrzzkk!
Luke: Holy crap. I need to regain control.
GM: Anakin's force of will is too strong for you.
R2-D2: Hah, now you know what it's like to have your mind hacked.
[SFX]: Whooom!
[SFX]: whooom!
Chewbacca: My apologies, the antivirus I developed won't work.
R2-D2: Yeah, not on such an unsophisticated processor.