In an interview with Forbes, Epic Games’ vice president and co-founder Mark Rein said that the company’s new iOS game Infinity Blade was already profitable despite having been on the market for only a week, leading to its title as fastest-grossing app. Rein didn’t disclose how much money the game has made, but the report notes that the game has more than 300,000 users playing on Apple’s Game Center social gaming network; at…