Rocket League is the game that came completely out of nowhere and pretty much blew everyone away, because who can resist car football? The mechanics are simple but extremely fine-tuned, hence why even the base game can easily eat up 50 or 100 hours of your life before you know it. That's without even discussing the array of free DLC content, adding a bunch of wacky mutators into the game as well as a hilarious winter-themed ice hockey mode, and much, much more. There's not much more to it than a basic sports game, and yet more so than any other game over the past 12 months, it's had us coming back time and time again even when bigger and more ambitious games have come and gone. More than a silly indie you'll play feverishly for a month and then forget about, this is a title with true staying power. Which 2015 video games have you got the most mileage out of? Shout them out in the comments!