Halo: Combat Evolved sold the original Xbox almost single-handedly, and it did it by fixing the console shooter. Two weapons at a time, a recharging shield, and a control layout with grenades and melee on shoulder buttons - that scheme is now the default for the entire genre.
The enemies were the other half. Bungie built the Covenant with genuinely different behaviours, so Grunts panic, Jackals shield, and Elites flank, and every firefight becomes a small tactical problem rather than a shooting gallery.
Master Chief works precisely because he barely speaks and never removes the helmet. He's a silhouette with a reputation, which leaves Cortana to do all the emotional work - and the relationship between them ended up carrying the whole series.
The energy sword remains one of gaming's great weapons, mostly because of the sound it makes.
This collection covers Spartans, Covenant weapons and Halo iconography.