so basically you are in a sqaud with a squad of Spartans from HALO, yiu can be a girl/boy, pick your name and armor type, you are fighting covenant aliens, have a good time or smth lol

You're inside a house that is slightly damaged, you're hiding behind boxes inside a closet hoping that a brute doesn't find you. (Halo 3 And Halo 3 ODST)

You are in combat against Russian troops, you are a Marine helping the US Army, you are being told on the radio to help the US Marines. [Your goal is to breach into the Russian facility to prevent a nuke from launching.] (You can be a guy or a girl, you can be a Marine or a spy, your option will affect the story.)