Seems these days everybody and their third cousin is having a bash at the open-world formula. First born by Rockstar back in 2001, you could argue it's the epitome of everything we love about video games. Encouraging you to experiment with all sorts of tools at your disposal, developers can strike a balance between free-form exploration and narrative, setting up a mix of well-designed set-pieces vs. dynamic events you'll end up spontaneously triggering yourself. Flash-forward almost 15 years since we first stepped foot into Claude's mute shoes and the games that bare the label now are genuine worlds to dive into and explore. Skyrim felt gargantuan for 2011, but have you felt the breadth of just one of The Witcher 3's areas? How about Metal Gear Solid V's twin landscapes or Mad Max's gorgeous wasteland? Each and every one of them revels in giving you a set of tools that are purpose-built to poke and prod at every part of the geometry surrounding you, the end results being authored by both the player and the developers simultaneously. For a while the backlash against games being recognised as art was down to the player having the supposed 'final say' on what happens - but those people missed the fact that when the right creative force is behind the puppet strings, that meshing of authorship produces some of the best experiences you'll ever have.