Do you remember GM's dialogue? He essentially said two things:

1. I'm feeling sorry for myself (I've been punished/imprisoned for a crime I didn't commit)
2. it's really quite peaceful if you just surrender and join me

You could never accept his offer because death just puts you back to a checkpoint.

But what if there was a skull hidden in a Flood level that, when active, when you die... an infection form Floodifies your body and you get to hunt and kill your allies.

Their AI reacts in fear and horror to your Flood state and you get to hunt and kill them. It would be a bit like an opposing force mod but built into the game.

Or if GM was allied with your allies at the time then you get to fight along side them but as a Flood.

Perhaps you could detach your infection form from your body and run along walls and ceilings or under walkways like wot Stubb's hand could do. You could infect enemies to take over their bodies and fight as them or convert them to carrier forms and explode amongst a collection of enemies. You'd be able to jump very far.

This is just for fun and you'd get various achievements for the different things you could do when playing as a Flood.

If you die then you are reincarnated in an infection form and have to take over an enemy body or make your way back to reanimate your own body.

If you kill a distinguished ally then their body becomes available to you too. (By distinguished I mean, a Spartan or the Arbiter, etc.)

Maybe you could help the Flood win for once. A level could flip if you are playing as Flood. For example: The Halo 3 level where you fight to the control room would flip to where Elites and marines protect the pyramid from waves of Flood.

You could still shoot your weapons so you wouldn't be limited to Stubbs' melee only gameplay but your melees would be really strong and your thrashing arm would be pretty long.

What do you think? On the unlikely event that the Flood comes back, just for kicks, do you think it would be fun?