It forever changed: Perk-based online multiplayer. These days you can't walk 10 feet without either walking into something resembling a perk-based multiplayer or a left-trigger/right-trigger shooting mechanic. Sure that might be a little extreme, but can you remember the last time you played a first-person shooter that didn't employ the 'hold up gun, shoot down sights' tactic? Even the leaked footage for upcoming Halo 5: Guardians showed 343 Industries are taking a hefty chunk of pages from Activision's finest, and its the twinning of these proficient mechanics with a sci-fi sensibility that's already endeared Destiny pretty deeply into so many players' hearts. When Modern Warfare dropped, you could genuinely feel the industry heaving to keep up. Call of Duty had long-since been running to catch-up with childhood-favourite Medal of Honor, and even though that D-Day landing level was going to be hard to beat from MOH: Frontline, Modern Warfare raised the stakes by actually having your hero die amidst the fallout of a nuclear explosion. Naturally you'll now be thinking of Modern Warfare 2's No Russian level and all the controversy it brought with it, and although that stellar second game is some players' best COD of all time, the big cultural shift that helped ingratiate video games into mass appeal overall was down to this first monumental masterwork.