Whoever says the original is always better should take a good look at this list. These superb games are united in their inventiveness, improving upon a franchise's strengths to deliver a fresh experience that renders the previous game almost obsolete. These are some of the best iterations in the industry...
5. 'Resident Evil 4'
Forget reinventing the franchise; Resident Evil 4 reinvented the genre, setting the gold standard for third-person shooters to follow. Capcom's brutal survival game evolved the series' tried and tested mechanics, introducing an innovative new inventory system, as well as a positively terrifying sack-headed chainsaw fiend. I still experience sweat-inducing flashbacks, the sounds of rust-colored metal gnawing at me in the night.
4. 'Mass Effect 2'
Far and away the best installment in BioWare's epic sci-fi trilogy, Mass Effect 2 still holds its own as one of the finest action RPGs ever made. Following in the footsteps of The Empire Strikes Back, this dark middle chapter sees Shepard and his crew embark on a suicide mission that can play out in a multitude of ways. The engaging characters, superb writing and spectacular environments made this sequel a joy to play.
3. 'Portal 2'
When the first Portal was released, becoming an instant phenomenon, it was difficult to see how Valve could possibly improve its ingenious puzzler. But with a slew of incredible voice talent on board, the developers crafted a game superior to its original in every way.
2. 'Grand Theft Auto III'
Of all the games on this list, GTA III is the one that pushed things forward in the most radical way. Switching from the series' classic top-down perspective, Rockstar's open-world crime sim introduced a new dimension to its graphics and gameplay. It's hard to think of a more ambitious sequel than this game, throwing out all previous conventions and replacing them with a formular that's still copied to this day.
1. 'Street Fighter II'
What can I say about what is perhaps the most influential fighting game of all time? Street Fighter II's significance can only be truly appreciated when you look at how stripped down its predecessor was. If you didn't pay attention to titles, you'd be forgiven for thinking each game belonged to a totally different franchise. This sequel took a fairly average game and made it into an extraordinarily well-balanced fighter that's still popular in the competitive scene, which is is why it earns the top spot on this list.