If you grew up playing video games and you're now somewhere in your mid-twenties... lucky you! After all, you were young enough to bask in the glory of old school systems like the SNES and Sega Megadrive, but you were there when things really started to get good - when video games made the leap and transitioned into something more. Hopefully, then, growing up in an era where video games came into their own gave you the opportunity to experience all of the wonderful things that gaming has to offer in the space of a short period. It'd be difficult to get to grips with all of cinema - or, indeed - literature in the same timespan as it is possible to get familiar with the gaming medium; after all, the video game medium is a young one; "new," in the grand scheme of things. So how familiar are you? How many of the most essential video game titles have you experienced? Can you honestly say that you've tasted the best of the best? What follows, then, are those games that define the medium. These are the titles that progressed, morphed and transformed video games for the better, steering them in new and unexpected directions. They inspired pop cultural insanity, amassed global attention, and - occasionally - changed the world. Some of the titles here might be described as works of genuine art - as beautiful and memorable as any painting by Rembrandt - whilst others are just awesome in their sheer playability. Here are 25 video games that everyone - boy, girl, man, woman, dog, cat, alien, plant, mineral - should have played by the ripe old age of 25, starting with...