I have a gametype that I’ve already tested extensively, so I’ll just leave this here as advertising. 
Game-mode name: Alien vs. Predator
(Link to game-mode)
Halo version: Halo 4
Game type used: Flood
Category: Flood with a little bit of Action Sack
Number of required players: 6-10
Teams: It’s Flood, so you decide. 
Description:
A revamp of the Flood gametype that places you in the shoes of two of the most iconic Sci-Fi characters. Humans take on the role of the Predators while the Flood are the bloodlusty, fast-spreading Xenomorphs.
Predators spawn with Binary Rifles, Energy Swords and Pulse or Plasma grenades based on your loadout choice. They have permanent Camo and infinite Promethean Vision, but no motion tracker. Predators are also more agile than standard humans. Their goal is to kill as many Aliens as they can, while keeping themselves hidden. Ordnance on the map as well as Personal Ordnance are enabled for Predators, and are modified to offer the complete non-human arsenal of Halo 4. I made sure that every weapon is useful as well, even the Plasma Pistol. :3
Aliens are very similar to default Flood. They have access to the default Flood loadouts, including the infamous Thruster Pack. However Thruster Pack is no longer the all-powerful choice, though still useful. Promethean Vision and Camo are very useful counter-abilities against the Predators. ProVision allows you to see careless Predators trough walls for a short amount of time. Active Camo allows the Aliens to stay hidden from the Predator’s view while crouch walking or not moving. Finally, I have tweaked the gravity settings so that Thruster Pack is nerfed a little bit.
Aliens have motion trackers, so if you’re playing as a Predator you have to be carefull not to reveal your location. Crouch walking will allow you to stay hidden from motion trackers and Promethean Vision. Try to find the right mix of stealth and combat to be a more efficient hunter!
I think AvP offers a new way to play Flood. The tactics you’d use in normal Flood are now completely turned around. An example of gameplay change is that humans and Flood both have Energy Swords, which often results in Sword-clashes.
Requires novel Forge map: No
Recommended maps: Medium-sized maps. Due to gravity tweaks I would advice against maps that rely on gravity lifts i.e. Haven and Adrift.
Personal Recommendations: Abandon, Solace and Landfall.
Type of test requested:
As I said I have already tested the gamemode, done a lot of tweaks and I’m confident of its balance. The last update I’ve done to the gamemode was in januari and I haven’t run into any obvious issues since. I’m considering on turning off the instant respawn and killcam though. Nonetheless feedback is always appreciated. 
Edit: Killcams and IR removed. Also tweaked Flood damage to make Overshield more useful.