HALO is OSR

search your feelings, you know this to be true

Think about it. Master Chief has limited inventory slots (two for guns, two for grenades) designed to force the player into making interesting choices and tradeoffs. If you pick up a powerful but overly specialized weapon like a sniper rifle, gravity hammer, or rocket launcher then you'll be less flexible in situations that those weapons don't excel in, but if you keep to your solid foursquare meat-and-potatoes loadout of battle rifle and shotgun/pistol you may find yourself outgunned or outranged in a key moment. Sometimes you'll just run out of ammo for the better weapons and need to scrape by on readily available trash-tier equipment like the needler until you can scrounge something better, a design philosophy meant to generate tense moments and force the player out of entrenched habits (or learn why the plasma pistol is actually good). 

Halo also uses a two-track HP system with a large pool of easily regenerating ablative HP and a smaller one representing real injuries, which requires a limited resource to restore. The Chief spends a lot of time exploring ancient ruins, interrupting destructive alien rituals, and fighting eldritch tomb-spawned horrors. 

Plus, you can honk the little horn on the mongoose ATV.