Gears of War: E-Day is a terrific game and it has the highest Metacritic score of any entry in the franchise since the original Xbox 360 trilogy. But early estimates suggest the positive buzz has not resulted in blockbuster sales numbers. That makes it an interesting test case for Xbox’s return to exclusivity, especially for a game that cost so much.

The first rumors of Gears of War: E-Day ‘s budget arose in June after it was shown during Xbox’s summer showcase. Insider Gaming ‘s Tom Henderson said at the time he’d heard the cost to ship the shooter was “insane” and over $400 million. Windows Central ‘s Jez Corden pushed back on that claim. He suggested the budget was lower and that accounting for the cost of The Coalition is tricky because of the work the studio does supporting teams across Xbox Game Studios.

But according to one source familiar with Xbox’s business, the cost of Gears of War: E-Day is in fact much higher. They told Kotaku it was over $500 million, and that’s before you include marketing.…