Thompson, who is under investigation by the Florida bar after a series of complaints, said that a character in the game is a lawyer who says: 'Guns don't kill people. Video games do.'
The anti-gaming lawyer stated in a letter to Take2 Interactive chairman Strauss Zelnick that he is worried that gamers will copy the game and put him at risk.
The first mission in the game involves the lead character having to gain entry into a lawyer's office and shoot the lawyer.
The letter also claimed that GTA4 developer Rockstar Games alleges on its website that Thompson is bisexual, something which he says has led to his wife being sent sex toys by gamers.
This is not the first time that Thompson has claimed that he has been parodied in a video game.
The lawyer has already complained that Midway Games showed an avatar of him in Mortal Kombat: Armageddon.
He has also sued a former US Attorney General for battery after she touched his arm.
Thompson has been a thorn in the side of the US computer games industry, and has taken repeated action to stop what he believes are harmful games.
The lawyer claimed in April that the Virginia campus shootings were down to the killer's video gaming habits, and has pioneered laws that ban the sale of computer games to minors even though these have been struck down by the Supreme Court.
US lawyer seeks to ban GTA 4
By Iain Thomson on Sep 21, 2007 12:17PM