Initially planned to be a "$7 million range" project concluding around 2007, the America's Army series continues to this day, with the Army claiming that it is a more effective recruitment tool than "any other method of contact." nope
The most expensive game known, Grand Theft Auto IV, is estimated by developer Rockstar to have cost roughly $100 million. Sega AM2's Shenmue, initially released for the Dreamcast in 1999, previously held that crown with its $70 million budget.
The third major America's Army entry arrived on PC this past June, after which the Army shut down its main Emeryville, CA-based studio and relocated development to the main program office in Redstone Arsenal, AL. Thanks to roushimsx for the heads up.