Well, I didn't read all of the suggestions in the thread, but I did read the first page and a bit of the last.
So sorry if my ideas are similar to other people's ideas, I wouldn't know.
Also, I will use Black Ops 1 guns as examples unless I say otherwise.
So there has been a lot of controversy whether there should be ranking up in zombies, and what you will unlock for ranking up.
We all know that unlocking new guns when you level up would be unfair, because that means a noob would have little to no fun, with only the M1911 and Olympia or something.
But I thought about Team Fortress 2 and how you unlock new guns that aren't better, just different. So how about this idea:
Every time you level up you gain 100 Zombie Points. There will be a max of 50 levels, like in normal multiplayer. You can then go to the zombie armory and spend these points on special weapons and other stuff. These weapons will not give you an advantage, they will give you an advantage AND an equal disadvantage.
Lets say you want to upgrade your M1911. You are at level 7 now, so you have 700 Zombie Points. You go into the armory and choose M1911, and there are guns available for purchase. Be aware that you must unlock some from special challenges.
Lets say if you reach level 5 you unlock a new gun: The Popper. It will cost say 150 Zombie Points to buy, and this is how it works.
Once you buy multiple upgrades, you have to choose which one you want activated. So lets say you buy the Popper and activate it. Now when your next game starts, you will start with the Popper instead of the M1911. It will have a new model and skin, and some specific pros and cons. Lets just make a random example:
The M1911:
20 Damage (1600/MaxAmmo)
X3.5 Headshot (5600/MaxAmmo)
80 Max Ammo
8 Mag Ammo
Semi Auto 600 RPM
The Popper:
16 Damage (1024/MaxAmmo)
X6.5 Headshot (6144/MaxAmmo)
64 Max Ammo
8 Mag Ammo
Semi Auto 600 RPM
Also, if you upgraded any other gun, once you buy it off the wall you will get your activated one. So lets say you upgraded the Raygun, now if you get the Raygun in the Mystery Box, it will be your upgraded activated one, but if your teammate gets it in the box, they get THEIR upgraded activated one.
You could also upgrade grenades, perks, pack-a-punched guns, and most other material goods.
This would be not easy but not hard either for treyarch to implement, because you only need a few guns (5x the normal amount) and it would allow SO MUCH variation.
And remember, you can always prestige to reset your upgrades and spend your limited Zombie Points on different guns.
And with the CONFIRMED zombie wager matches, you might gamble Zombie Points.
I just had a few cool examples of my system:
Frag Grenade Upgrade: Big Bang
To unlock: Kill 8 Zombies with 1 Grenade (no insta-kill allowed)
Cost: 50 Zombie Points
Effect:
-25% damage
+33% radius
Dragunov Upgrade: Dragon 50. Cal
To unlock: Purchase 25 Fire Related Items (fire traps, hades shotgun, flamethrower gun, flamethrower attachment, malatov cocktail, etc..)
Cost: 200 Zombie Points
Effect:
-20% Ammo
+ Zombies light on fire after being shot, fire does low damage but spreads like the wunderwaffe for up to 8 zombies. Lasts 8 seconds.
D115 Forest Fire Upgrade: D115 Igniter
To unlock: Purchase 100 Fire Related Items
Cost: 300 Zombie Points
Effect: -50% Ammo
+Zombies light on fire after being shot, fire does high damage and spreads like the wunderwaffe for up to 24 zombies. Lasts 4 seconds.
Monkey Bomb Upgrade: The Distraction
To unlock: Revive 50 teammates while a monkey bomb is active.
Cost: 100 Zombie Points
Effect: -33% Ammo
+ Lasts 50% Longer