Halo has been the forefront and staple of the Xbox ever since its debut in 2001, going on to shape the Xbox and Microsoft brand as a whole in the coming years. Halo: Combat Evolved, the first installment in the series, is revered as a classic for having launched the influential franchiౠse, and for good reason; despite being a first person shooter developed nearly twenty years ago, it contains world-building details that you would be hard-pressed to find in many current-gen games.
One such detail appears in the earliest levels of the game: the parasitic alien antagonists called T꧂he Flood can be seen observing you long before their official introduction in the game.
The Flood's first appearance is notorious among the Halo community for ramping up the stakes and leaving players fearing the unknown throughout a majority of the rest of the level. In a short cut scene, Master Chief picks up a marine's helmet and watches the footage of the entire group being killed and taken over in 🤡꧅what would be revealed as the Flood's main method of bolstering their ranks: taking over the bodies of their hosts and absorbing their intelligence into the hivemind.
In the introductory level 343 Guilty Spark, newౠ players will most likely not notice them. However, zooming into figures in the distance will show that The Flood is watching the player and the Covenant from the very start.
It's not the only allusion to the eventual introduction of The F🧸lood in this level: near the beginning, human blood and Covenant blood can be found on the walls and floors of the environments without any accompanying corpses. As the player will later learn, this is b💜ecause the human and Covenants who were present at the scene have all been taken over by the parasitic enemy.
In the original version it was much more difficult to see the Flood, but with the enhanced graphics and less fog in the remastered Halo: Combat Evolved Anniversary, they become easier to spot.
An interesting aspect of this early appearance is that they show up as friendlies in the player's motion tracker. Some players speculate that this is because the marines they took over are still emitting a transponder signal, which is plausible; however, as this is the only level in wh♋ich they register as friendlies, it's much more likely that this was part of the programming to ensure players could not engage them in combat.
Nevertheless, it's a neat bit of foreshadowing to a pivotal point in the ga𒉰me that makes the plot and the setting that much more organic. It's obvious that the devs put an incredible effort into fleshing out Master Chief's world from the very beginning of what is now one of the most iconic video game franchises in history.