4. Call of Duty
While in its early days, Call of Duty was a niche shooter of sorts, its leap to consoles certainly helped broaden its appeal, and by the time Call of Duty 4: Modern Warfare rolled around, the series was gearing up to become a box office juggernaut. With a more cinematic approach than any similar game, as well as superb set-pieces, and most of all, a game-changing multiplayer component, Modern Warfare kick-started the annual release pattern of the Call of Duty games, that has seen four subsequent annual releases, with a fifth, Black Ops 2, due for release in just a short number of weeks. While each CoD game so far has raked in more cash than the one before it, surely that trend is going to come to an end soon, given the formulaic nature of the series, crassly resembling a FIFA or WWE game, in as much as it leaves its central mechanics in place and simply updates the graphics, characters and so on. That's not all, though; exorbitantly overpriced DLC, a subscription service called Elite, and giving away Double XP rewards to those who purchase the game in preferred stores all reek of a series that has well and truly gotten out of hand. Of course, it's a fine business model for Activision for now - because the CoD games have a hugely broad appeal, and casual gamers in particular can't wait to get their hands on them. That said, Black Ops 2 is at least taking something of a risk by setting itself in the future, a move that I expect might dent its financials more than Activision is expecting. But given their success so far, I'm probably wrong.