Here’s a neat bit of imagery I noticed at the end of the Halo: Reach game.
Some backstory (and spoilers, obviously): your player-character arrives on the scene in the beginning of Reach, on the planet Reach, as the replacement for the Spartan’s recently-KIA sixth member. Hence, your player’s name is Noble Six.
The end of the game involves Noble Six having to provide cover for a ship, the Pillar of Autumn, leaving Reach that is carrying an AI construct crucial for the human side of the war. Noble Six is essentially left behind as all the human military forces have evacuated the planet, and he’s left to fend off Covenant forces by hand. This last mission is called “Survive,” even though to complete the game you have to be killed.
Besides taking out as many Covenant soldiers as he can, the Covenant end up glassing the planet anyways, killing all life on it.
Without Noble Six’s sacrifice, the war may not have turned out the way it did. The last scene shows Noble Six’s helmet on the ground at Reach. There’s a large mountain in the background with a large vertical gash, symbolic of Six’s sacrifice and impact on the Human-Covenant war.