So, you beat the Halo demo. Even if you never played Master Chief's debut entry back in 2001 (or 2003 on PC), there's a good chance you know about The Silent Cartographer. Halo: Combat Evolved's fourth mission is a masterpiece of level design, a compact showcase for Bungie's FPS sandbox and, as the level chosen for the game's wildly popular demo, likely the most instantly recognisable mission in the entire series.
It is not, however, the blueprint for Halo Infinite's open world.
You'd be forgiven for thinking it was, of course.