The last big Rockstar game, Grand Theft Auto IV, cost roughly US$100 million.
The most expensive game (well, before Grand Theft Auto IV) was SEGA's Shenmue, which came in at a cool $70 million to develop. But in 2008, Rockstar producer Leslie Benzies guestimated that GTAIV cost about $100 million.
According to the UK's Daily Mail (yes, yes, I know), Red Dead Redemption is giving GTA a run for...its money. From the paper: "Makers Rockstar Games are thought to have spent up to $100million on the long-awaited project."
No word on where that figure came from. The game was first shown in 2005 and had a rocky development, it seems.
Kotaku is following up with Rockstar and will update if the developer comments.
Red Dead Redemption: Groundbreaking video game lets players relive the Wild West | Mail Online [Mail Online Thanks, Sweet Music!]