Players in MadWorld use chainsaws, spiked clubs, daggers and spears to execute victims.
They can impale their enemies on road signs, fry them on electrical sockets and rip out their hearts.
The game's 'bloodbath challenges' see characters mown down by trains, crushed in the back of refuse collection vehicles and blown up as 'human fireworks'.
A challenge called 'human darts' sees players pick up Madworld citizens and hurl them onto giant spiked dartboard.
Sega, publishers of the game, said it is "tipped to be the most violent video game in history".
Its launch saw hundreds of artificial severed arms placed around the country clutching a copy of the game.
The game has already caused controversy abroad, being banned in Germany, while parent groups in the US have also called for a ban.
John Beyer, director of Mediawatch-UK, a pressure group campaigning for decency in TV, films and games, said the British Board of Film Classification, which granted the game an 18 rating, should instead have banned it.
He said: "I deeply regret the Board's decision. It is very well known that children and young people get access to 18-rated games.