First-person shooters, including Call of Duty, would incorporate this game's regenerating health system, forever changing the dynamics of the genre. Faced with the limits of the Xbox console, Bungie would force players to keep only two weapons at a time, introducing a new strategic element to the shooter genre known for giving players dozens of guns at their disposal at any time. Its music reacted dynamically to the player's on-screen progress and actions, a groundbreaking audio storytelling technique that's everywhere today. And, of course, it finally cemented the right analog stick's function to controlling cameras, forever changing how players would aim and look around in shooting games for the next two decades and beyond. Even after 20 years, it's remarkable how modern and evocative the Xbox launch title can be. "Halo: Combat Evolved" is a game so future proofed, it's as easy to pick up to play today as a Super Mario game would be to anyone who grew up in the 1980s.