Alright, it needs a lot of fleshing out because of how significant some of the gametype revisions are, but here's the gist of my proposed playlists. A big thing to keep in mind is that all playlists would have four voting options in this theoretical revision. The voting options are listed accordingly; "alternating" literally means they would switch in a binary fashion per vote screen.
Primary Playlists
Slayer
Kill other Spartans to earn points in a mix of Free-For-All and Team games. 8 Players.
Team Slayer Pro
Alternating Team Waypoint Slayer / Infinity Slayer
Alternating Team SWAT / Snipers
Slayer (Free-For-All)
Team Objective
Capture the Flag and Set Up Us The Bomb to earn points. 8 Players.
Capture The Flag
One Flag
Assault
One Bomb
Oddball (could potentially be renamed to Team Balls or something ridiculous)
Hold the Ball to earn points. Hold three Balls to earn points. Hold the explosive Ball to earn points (and explode!). Grif the Ball to earn points. 10 Players.
Oddball
Three Ball
Hot Potato
Grifball
King of the Hill
Stay in the Hill to earn points, lock down precious sectors, and reach checkpoints. 10 Players.
King of the Hill
Territories
Three Plots
Race (Free-For-All)
Secondary Playlists
Team Doubles
Go where the battle bros roam. Compete against a dynamic duo in a mix of Slayer and Objective gametypes. 4 Players.
-Team Slayer
-Team Waypoint Slayer
-Alternating One Flag / One Bomb
-Alternating Oddball / Regicide
Regicide
Kill the enemy King while defending yours. Regicide crowns those with the most points, while Emperors crowns the King's killer. 10 Players.
Team Regicide
Regicide (Free-For-All)
Team Emperors
Emperors (Free-For-All)
Big Team Battle
Large-scale squad skirmishes are back and bigger and better than ever with a mix of Slayer and Objective gametypes. 16 Players.
-Team Slayer / Waypoint Slayer
-Capture the Flag / Assault
-One Flag / One Bomb
-Territories / Three Plots
Conquest
Play a mix of larger-scale, tactical multi-tiered objective gametypes. 16 Players.
Extraction
Domain
Invasion
Random Extraction / Domain / Invasion
Living Dead
Fight off evolved undead hordes with your wits, military-class buckshot, and fortifications. 16 Players.
Flood
Flood
Safe Havens
Safe Havens
Double EXP
A rotational playlist that always provides Double XP. This would be where DLC listings, Community Cartographers testing, Grifball, Multi Team, etc. would show up.
TOTAL PLAYLIST COUNT: 10
Gametypes
Slayer Pro:
Classic Halo. No Sprint, higher movement speed and slightly higher damage, no Armor Abilities, preset Loadouts, 25m Sonar (enemies only show up on radar when they shoot), preset on-map weapon spawns. Instant Respawns disabled. No Personal Ordnance. 50 Kills to Win.
Waypoint Slayer:
A revised version of Infinity Slayer designed to have more arcade-y fun exploring more of the sandbox than Slayer Pro, but also having the potential to be competitive. Instant Respawns disabled. Personal Ordnance may or may not be enabled (but restricted) depending on community testing and opinion. Sprint enabled, 100% movement speed, 100% damage, custom loadouts available, 25m Motion Tracker, 60 kills to win. A few notable changes:
-Similar to Invasion Slayer, a small hill must be "locked down" by a team to receive an according Ordnance weapon. Hill sizes, lockdown, and weapon spawn times are reduced compared to Invasion Slayer.
-Rather than spawn a specific weapon, it will have in indicator displaying the weapon's tier: keep in mind this would rely on my sandbox, which has one weapon per faction per "category." For example, a "Sniper" indicator could show up, giving you an equal chance at getting a Sniper Rifle, Beam Rifle, or Binary Rifle. A "Wild Card" indicator could potentially get you a Grenade Launcher, Gravity Hammer, or "Gravity Wrench" (name pending).
Waypoint Slayer would arguably be the default Slayer gametype of choice, with Slayer Pro being more barebones and Infinity Slayer being more Fiesta-styled.
Infinity Slayer:
Pretty much exactly out of Halo 4. This is a dumb gametype.
Team SWAT / Snipers:
The gametypes you know and love. SWAT could possibly have on-map marksman weapons (DMR / Needle Rifle / Pulse Rifle) but it's debatable. Likewise to Snipers; Sniper/Beam Rifle and Beam Rifle/Sniper loadouts are available with the Binary Rifle being a potential power weapon.
FFA Slayer:
This would probably FFA Waypoint Slayer with some tweaks, like 25 kills to win.
Capture The Flag: Pretty much the same as Reach-era variations and previous. No instant pickup. You can drop the flag now (by hitting the Switch Weapon button) but you have reduced movement speed like in previous games. You don't have an active KILL waypoint, but the Flag will have an away indicator. Juggling the flag a total of 5 times in rapid succession will paint you with an indicator that lasts for 5 seconds after you stop juggling, regardless of whether or not you're holding the flag. It's possible to "let the paint dry" by only going juggling four times and carrying. Holding the flag also gives you the Flagnum, which is the Halo CE Pistol decked-out in gold and diamond plating. As a balance measure the range is slightly reduced but everything else about the pistol remains intact; it becomes naturally balanced by being slowed down by the flag again.
One Flag: See above for gametype changes.
Assault: The closest to "vanilla" the objectives get; bomb drops are available, user is slowed down, no Flagnum, all that good stuff. No instant pickup. Arming works like it does in Halo 2, though.
One Bomb: See above for gametype changes.
Oddball: Pretty much the Halo 4 version. No instant respawns, no ball dropping, but ball throwing is an option. Instant pickup is removed so you have to actually "negotiate" ball tosses between teammates. The only difference is the addition of a second ball dispersal option: the "Toss Grenade" button will still initiate a throw. However, the Right Trigger will let you roll it like a bowling ball, terrain notwithstanding. This offers more range and can be use for more covert passes. The Melee button can still be used to get ball kills.
Three Ball: See above.
Hot Potato: Reach's explosion mechanic meets Halo 4.5 Oddball. Instant pickup is enabled in this. A key difference is that the ball will begin to glow red and spark the closer it gets to detonation as a more obvious indicator. The timer will not reset from a simple drop; only getting the ball to stop moving will reset the timer. However, it will not explode until being held by a player, meaning you can bait enemies by bowling-rolling it down a corridor at an unsuspecting enemy who will try to pick it up and subsequently explode.
Grifball: The bomb passing/physics of Halo 4 met with the actual sport rules of Halo 3. Explosions and rounds return!
King of the Hill: The Halo 4 version save for Instant Respawning. King of the Hill was actually given pretty nice treatment in terms of game mechanics, too bad they killed it off.
Territories: Classic Territories. No Instant Respawns, up to 8 possible territories depending on map (though unlikely at this team size).
Three Plots: Locking down a territory will do so permanently and earn you one (1) point. No Instant Respawns. Locking down all three territories essentially activates a "Bonus Round" of 30 seconds at the end of the round similar to Dominion with the losing team having Overshields and one life; if the winning team can kill the entire team that's in Sudden Death, they can earn an additional point.
Race: The Reach version, basically. It's FFA instead of 5v5 like the other games in the playlists and warns you accordingly.
Regicide: Identical to the Halo 4 version.
Emperors: Regicide, with the sole exception that killing the king makes you the king rather than the most points, essentially making it a Juggernaut reboot. You can earn the most awesomely-voiced medal in the game in this gametype. "Immmmperialist!"
Extraction: Pretty much identical to the Halo 4 version. Predominantly UNSC aesthetic.
Domain: Reskinned Dominion with a predominantly Forerunner/Promethean aesthetic, but with lowered power weapon/vehicle weightings.
Invasion: Gametype options are as functional and versatile as Reach's Invasion, but the gametype is always Spartan vs Spartan. Predominantly Covenant aesthetic with regards to objectives and whatnot.
Flood: Gameplay is slightly rebooted. Flood takes the first step into a true class-based system, evolving off of what Halo 4's version had. It starts out with 12 humans and 4 Alpha Zombies. Humans start off with more ammo to compensate for bigger maps and higher player counts. Players start with Shotguns and Pistols, while the Flood get classes, explained in Safe Havens. Alpha Zombies have shields and are red. Traditional Zombies are Flood-colored, and Omega Zombies are jet black, also explained in Safe Havens.
Safe Havens: A radical step above Reach's version. Somewhat radically, it should be noted that traditional kills as a zombie will not infect an enemy player. Similar to Dominion, you can capture bases. Humans capturing a base will allow them access to the base's technology and provide them with a fortifiable area, with varying base numbers on maps, usually 3-5 given the large player count. Classes don't open up for humans until a base is captured, at which point they also get access to Instant Respawns. If a human stays in the base for a consecutive minute, it allows them to request a Personal Ordnance drop, which is much more restricted than Infinity Slayer. Close-quarters weapons are not offered to prevent camping. Instead, you can spawn things like DMRs and Railguns.
If the Flood successfully capture a base, it becomes an Incubator. An Incubator allows the Flood to spawn instantly and opens up the Omega Zombie class. The Omega Zombie is jet-black with shields (similar to the red Alpha Zombies), but also has the unique property of being able to infect humans. It should be an immediate priority for humans to disable an active Incubator, meaning the Spartans can't simply turtle in an area, but at the same time don't have to worry about trying to capture territory and get infected right off the bat. Additionally, after capturing a base, you can spawn fortifications, such as turrets, and there are two types of structural fortifications: Deployable Cover and Alt-Walls. Deployable Covers are shielded entrances similar to Dominion, requiring two strikes from a Flood Talon to break. They start out active after a base is captured. Alt-Walls are unbreakable, but due to their "touchy" Forerunner nature, they capture two entrances on any given point of a base; but they can only block one at a time. Hitting a switch at either alt-wall will make it switch spots, which can be useful if an entire swarm is attempting to come in through a single door.
Similar to vendors in Black Ops II Zombies, there are some stationary Armor Mod Nodes scattered throughout the map, with one per base: their effects cannot stack and they are only available for one player at a time with a 30-second cooldown. An Engineer must turn on the machine first, which is instant. Some Armor Mods include Speed Boost (Dexterity perk included), Damage Boost, Overshield, and possibly others if there are more than 3 bases per map, such as Active Camo.
Human classes:
Survivor
-The basic human class, armed with a Shotgun and Pistol. All loadouts come equipped with a Shotgun and Pistol; other weapons must be found on the map or called in.
Engineer
-Becomes available after capturing a base. This is the only class that can power up Armor Mod Nodes, activate and reactivate Deployable Covers, and initiate Alt-Walls. Engineers are slightly more sluggish than Survivors and Mavericks.
Maverick
-Becomes available after capturing a base, replacing the Survivor class. Designed as a class for those that don't want to help defend a base with their team. Shotgun and Pistol with double the ammo count, but you are unable to help your base in any way.
Flood classes:
Combat Form
-The traditional flood equipped with a Flood Talon and modified Thruster. Jump height is reduced compared to Halo 4's version, intended for horizontal movement.
Carrier Form
-Carrier Forms made from Spartans are noticeably more bulbous than Combat forms, but are not large enough to incubate Infection Forms themselves. Instead, they rely on their ability to explode, using the miniature nuclear reactor in the suit to create a wide area-of-effect explosion which has the potential to kill in closer ranges. The Carrier is the ultimate camping denier. However, it is the slowest of the classes and also has the lowest jump, and being more bulbous means it is much easier to kill. Relying on the nuclear reactor, the Carrier must initiate its explosion manually; simply killing it will not cause an explosion.
Override Form
-Infected higher-ups such as ONI officials. The most frail of the Flood classes, they have low jump heights but are faster than a Combat Form, though Combat Forms have an advantage of more agility due to their Thrusters. Their weapon is a ranged, arcing flurry of spikes similar to a way weaker Ranger form. Firing is similar to dual spikers but actual damage isn't good enough to kill in a one-on-one fight; it's only meant as suppressive/covering fire or distracting players. The real use of Override forms shines in its Infector Talon, which can be used to instantly disable Deployable Covers and activating Alt-Walls from the outside. It can also be used to infect players even if an Incubator isn't active yet, however, it requires two sustained seconds of activation on a Spartan, meaning that unless they're trapped and alone infecting them as an Override form is unlikely.
Ranger Form
-These forms have the speed of a Combat Form with no Thruster (so average), the health of an Override Form (so slightly below-average), and very high jump height. They can use a Jump Jet to hop in a large arc similar to Jump Pack Brutes, allowing them to invade fortifications from the top down. They also have no hand-based weapon; uniquely, they have talons built into their ankles and heels, meaning that landing on a Spartan after a jump is an instant kill.
Omega Form
-A shielded, jet-black Combat Form with the capability to infect Spartans by killing them. Only available when an Incubator is active.