It means specifically THAT battle that it plays in. Here's line by line.
(They Fall in line, one at a time) You kill them one at a time.
(Ready to play) They fight back.
(I can't see them anyway) There's a lot of cover and they can hide.
(No time to lose) Kill them before they kill you.
(We've got to move) Keep moving.
(Steady your helm) Don't miss.
(I am losing sight again) It's a dark room.
(Fire your gun) Um, SHOOT THEM!
(It's time to run) Move too slow, They shoot you.
(Blow me away) You fight Hunters.
(I will stay, in this mess I made) He, The Master Chief, started this by killing Regret.
(After the fall, We"ll shake it off, Show me the way.) After you die, you respawn and go through the same door.
(Only the strongest will survive) You have to be the last thing standing for the doors to open.
(Lead me in heaven when we die) Again, you respawn.
(I hear a shadow on the wall) You fight cloaked elites at the end.
(I'll be the one to save us all) The Chief is fighting for all of humanity.
(There's nothing left, so save your breath) The Elites at the end are supposed to be reinforcements for Elites, but the battle is already lost.
(Lying in wait) You hide a lot to avoid being shot.
(Caught inside this tidal wave) It's a HUGE fight.
(Your cover's blown) They realize you're there after a little bit.
(Nowhere to go) The doors lock behind you.
(Holding your fate) Keep your gun handy.
(Loaded, I walk alone) You're on your own, find your own ammo.
(Wanting it back) Galactic peace?
(Don't fight me god!) Everything goes against you.
(Here I come!) You do the majority of the killing.
(Die!) Kill, kill, kill. I think there's strategy in this battle somewhere.
(Save us all) Again, he's fighting for humanity.
