June 19, 2008: This writeup is in the process of an overhaul.
June 5, 2009: Yeah - still needs an overhaul. I'll do it soon. I don't get much time for noding these days.
Of all the bad guys that I have ever faced in a video game, none are quite so disturbing as the Halo series of video games and novels.
I should probably warn you that this write-up assumes that you have played the Halo games, and are deliberately looking for more information on the Flood. Therefore it includes copious spoilers. If you have not played the video game, and don't wish for me to absolutely ruin it for you, I would highly suggest that you go read something else.
You've been warned.
The Flood is the collective term for a species of parasite that was discovered by the Covenent and Humanity on Installation 04 (the halo) and are now known to inhabit Installation 05. There are several manifestations of the Flood, which I will review below. The Flood first appear in the level entitled 343 Guilty Spark of Halo: Combat Evolved. This level begins in a swamp which was the last known location of Captain Jacob Keyes. In fact, that's the man you're trying to locate at the behest of Cortana who knows that Keyes is about to release something vicious and uncontrollable.
Well Enough Alone
As you begin your trek through this swamp you discover a crashed human ship, and very nearby a crashed Covenant drop ship. You also run into a few straggling Covenant Grunts and Jackals who are panic-stricken and running from... something.
Being naturally curious, you go in the direction from which these Covenant are running. After all, the enemy of my enemy is my friend, right?
You locate a structural entrance into some sort of base which delves pretty deeply into the crust of Halo, and after a few elevator trips downward, you start to notice that it's gotten very quiet. Too quiet. Almost no human or Covenant presence, but plenty of human and Covenant viscera. You locate a sole human, who is quite obviously suffering from the effects of post traumatic stress disorder, and he begins to shoot at you, and utters the cryptic phrase:
Stay back! You're not turning me into one of those... things!
Unfortunately, you have to extinguish his flame. As you continue deeper, you run into PFC Jenkins, who falls into your arms and dies. You are then introduced to The Flood by way of Jenkins' helmet recorder, which provides a video detailing the final moments of Jenkins' life.
It is at this point the game of Halo irrevocably changes. The Covenant are still your primary enemy - but with the introduction of the Flood, they are often distracted, as they are also battling the Flood. Also the orderly combat scenarios in which you've thus far been engaging (an Elite or Honor Guard leading packs of subordinates Jackals and Grunts, for instance) become chaotic and frenzied.
The flood appear to be terrifying alien zombies. They are, in actuality, parasites (not unlike the Head-Crabs of Half-Life), which worm their way into their hosts' nervous systems, and spawn whip-like appendages, which are used as weapons. They are incredibly agile and they lack the capacity for pain, and are completely negligent towards the integrity of their host bodies. This makes them incredibly strong, fierce and fearless.
What makes the Flood especially unnerving is that they are not evil, or fueled by zealotry or conquest - as are the Covenant. Their only desire is to feed and reproduce. They are parasites, nothing more. However, it seems that halfway through Halo 2, they appear to be evolving into something more: they appear to be displaying heretofore unseen intelligence, displaying knowledge of vehicle and tactical aircraft operation. This continues through Halo 3, where towards the end of the game they appear almost orderly, as if they are developing a strategy, which of course they are under the guidance of the Gravemind. However, they remain remarkably careless and haphazard in their control of vehicles and weapons, but this is primarily due to the Flood's inability to harness their host-body's fine motor control skills. When it comes to operating vehicles, they will grab any vehicle that moves, and simply direct it toward a potential host, and jump out of the vehicle at the host, leaving the vehicle to careen wherever it will. This follows for flying vehicles as well.
There are several flavors of the Flood:
Proto-Gravemind Form: This thing appears once in the games, although nearing the end of Halo 2, there are suggestions that there are more. There are things which resembled the protogravemind form, but it's inconclusive if that's what they actually were. At the end of the level entitled Keyes in Halo 1, (the object of which is to find and rescue Captain Keyes) you locate him. Unfortunately, he's beyond rescuing. It appeared to be a massive pulsating Carrier with a human(ish) face poking out of the front.
- Warrior Form: The Warrior form Flood are the dangerous ones. They were once humans and Covenant Elites who have been killed and overtaken by the Flood. Their heads lie limply and uselessly to the side and the arms are used only to heft weapons. Their primary appendages are whip-like branches which poke out from the host body, as do the sensor stalks, which the flood use to "see" their enemies. These whip-like appendages are also used as weapons to bitch-slap any Covenant or human that dares interfere with it. The Flood in this form are capable of superhuman (and supercovenant) strength. They jump unbelievable distances, they are extremely fast, and they pack heat. The upside is, they do not notice when you throw grenades at them. They aren't terribly bright, and they do not work cooperatively with other Flood. A shotgun blast is enough to drop one.
But be careful, they oftentimes get back up after you think you've killed them.
Uberbanana reminds me that Infection forms can regenerate fallen warrior forms. (See Infection Form below for more information on Flood Infection.) This doesn't happen in Halo 1, but in Halo 2 you can sometimes watch infection pods slip into fallen warriors to get the corpses back into the melee.
In Halo 3, a new twist has been added, in that when a Human or Covenant NPC dies, you can watch the Flood infect them and turn them into a Warrior Form - at which point they will begin to attack you.
- Carrier Form: Walking meatballs that blow up. Jackals and Grunts do not impress the Flood. Therefore they don't use them as combat units, they use them (and also humans who have been damaged badly enough that they are no longer combat effective) as spore dispensers. They appear as huge waddling sacs. When they are damaged or when they get close enough to a potential host, they drop and explode, sending Flood Infection and gray-green liquid everywhere. The explosion is quite damaging if you're unlucky enough to be near one that pops.
- Infection Form: This is the Flood at its basest form. They appear as little scurrying pods. They are very vulnerable to physical attack (one shot from a simple pistol is enough to wipe out several, or you can simply squash them by running over them), but they compensate with sheer numbers and speed. When attacking en masse, they look like a tidal wave of pods bearing down on you... thus the name The Flood. These are the critters who actually infiltrate a human or covenant body and turn them into a Warrior or Carrier.
- Pure FormsWhen the Flood has collected enough biomass it can generate self-sustaining forms which do not require a host body. These forms can shift from one to the other at will depending on which circumstances are most favorable to them. These pure forms come in three varieties.
- The Tank Form: This form is the pure forms equivalent to the warrior form. It is a slow, yet massive body which exhibits great strength when attacking, and resistance against attacks.
- The Ranged Form: This form attaches itself to the wall or floor, sprouts quills, and shoots them enemies with extreme accuracy from a distance.
- The Stalker Form: This form appears insect-like and scales walls trying to gain a tactical advantage before transforming into another form to attack. The stalker forms do not attack themselves, but are used as scouts and shift shapes when ready to engage their enemy.
Gravemind: Seemingly unique form of flood. The Gravemind is an enormous Venus Fly Trap looking creature that speaks with a loud resounding guttural voice, and forces the Master Chief and The Arbiter into alliance. He's also taken The Prophet of Regret hostage as well as 2401 Penitent Tangent (Monitor of Installation 05, which is 343 Guilty Spark's counterpart). The Gravemind does not look like or act like any other flood - and the only reason we know that he is Flood is because The Arbiter refers to him as such: "Kill me or release me, Parasite, but do not waste my time with talk!" The Gravemind's true nature is somewhat mysterious, but my theory is that he's some sort of "central" flood mind. Like the Borg-Queen, although as I mentioned before, the Flood act like individuals who are unaware of other individuals. They do not cooperate with each other, nor do they act as a unit. So a hive-mentality would definitely be a contradiction to what we know of the flood so far.
Further bulletins as events warrant
One of the things that bothered me about Halo 2 (and maybe it will be rectified in Halo 3) is the lack of certain Flood types that would have been logical to include. There were two new species revealed to be in the Covenant forces: Drones and Brutes. Drones are insectile creatures which can fly and wield weapons, and Brutes are incredibly strong. Both would have made intensely challenging Flood members.
But, I suppose I can write these off: The Brutes are too tough for the Flood to take down. In fact, there is one cut scene where the Flood try to attack the Covenant hierarchs only to be completely and utterly destroyed by the Brutes almost effortlessly. So the Brutes are safe by virtue of their sheer strength (although, as many Brute corpses left behind by the Master Chief, you'd think one of the Flood would have taken over at least one).
In the case of the Drones, other than their ability to fly, there's not much too them. They're green airborne wussies. The only value they'd provide the Flood would be air superiority, but given the Flood's lack of fine motor control within their hosts, they probably couldn't operate the wings adeptly enough for lift-off.
In my opinion, The Flood is of the most intriguing enemy species of any game, and I am really looking forward to their continued evolution in Halo 3 - if there is a Halo 3.