If I was apprehensive about anything in Halo 3, it was the Flood.
Halo 1 has reached a certain legendary status amongst fans, but even it has a sore spot for many: the Library, where you navigate endless repeating dark corridors with endless hordes of only four enemies to fight: Human Flood combat forms, Elite Flood combat forms, Carrier forms and Infection forms. The level goes on a floor or two longer than it really has to, and only has a few tricks up its sleeve to make it seem fresh.
If Halo is built on a foundation of "thirty seconds of fun" then the Library was built on six helpings of five seconds of fun: shotgun a Flood form in the face, run away, repeat.
Of course, other Flood missions fared much better; they had better unit mixes, more varied terrain and encounters, as well as vehicles. 343 Guilty Spark had atmosphere oozing out of every pore as the Flood gave you the first real scare of the game. Two Betrayals gave you the dark side of Assault on the Control Room as Flood, Covenant and Sentinels took aim at each other and you while you tried to stop Halo from firing.
The Maw mixed it up by varing your objectives a bit, and by allowing you the chance to watch some interesting fights play out. The Flood themselves, though, were interesting to look at, but not so much interact with. When they didn't see you, they gurgled. When they did see you, they charged straight at you, firing whatever they had. If you had superior firepower and room to maneuver, it was no problem. If you had only one of those, or neither, you'd be in a world of hurt, not because the Flood outsmarted you, but because they overwhelmed you with numbers and clogged up your travel lanes with dead bodies. Or even dead Grifs.
Halo 2 added a significant twist to the Flood, but the game could only get so much mileage out of it. Instead of merely giggling with glee as you set off cascading explosions of popcorn Infection Flood, this time around the little devils scurried around more unpredictably, and raised dead Flood from the battlefield to face you once more if you didn't dismember them with a sword or blow them up with a grenade.
Once so raised, though, they were still the same old Flood. Four flavors, and one tactic.
How, then, would Halo 3 handle the Flood? More of the same?