4.1 million downloads for the PC version.
According to TorrentFreak, Activision's Call of Duty: Modern Warfare 2 was 2009's most pirated video game, chalking up 4.1 million downloads for PC and 970,000 downloads for Xbox 360. The total of around five million downloads eclipses the 1.7 million downloads of EA's Spore in 2008.
The data for the list was collected by TorrentFreak from several sources, including reports from all public BitTorrent trackers.
Other popular titles for video game pirates included The Sims 3 (3. 2 million downloads), Prototype (PC/Xbox 360 - 3.16 million) and Street Fighter IV (PC/Xbox 360 - 2.69 million). Nintendo's New Super Mario Bros. Wii was the most pirated Wii title with 1.15 million downloads. No piracy data for PS3, PSP or DS was given.