Grand theft auto idea mining for rpgs

I was thinking of stealing liberty city for the backdrop to a mutants and amsterminds batman level game. Which sparked the diea that I could steal the city, lots of the missions and story for a spycraft game, and heck I could even make the city medival and use the missions, characters, town ofr a standard d&d game.

Admitedly I'm a grand theft auto freak and am counting the minutes until I leave work to play its latest incarnation, but does anyone else have vidoe/computer games they blatently steal from to create the rpgs they run, and if so what games are they?

Man I use all GTA cities in my games. Not only Liberty City, but San Andreas and Vice City. But no fancy things like super heros and mutations. The ugly life of a bunch os guys who want to put all the cities on their knees.
The ccharcters are:
Alex Spencer (strong hero 2): thug - from Liberty City
Jeff Loan (smart hero 2): ex-cop - Vice City
Lina Inverse (Charismatic hero): ex-model, ex-prostitue: Vice City
Charles Garcia Cortez Paul (fast hero 2): lawyer: San Andreas