Here are my suggestions :
-Create Ammo Kits & Medic kits.
reason: It's annoying that you must get to your camp,which manytimes it's too far away,but even if you get to your camp,it doesn't regain your ammo.
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-New types of game mode (NOTE: Those are connected & with a "style" Option )
Medieval:
Classes : Knights,Archers,magicians,priest.
New stuff: Swords,Bows/Crossbows,Staffs,Magic Skills,Mana,catapults,Rams,Horses...
Terrain : Castles,Villages,Wizard towers...
Point: Your Opponent castle has got your flag & you have theirs.To win,You must:
A) Assault; Raise your flag.
B) Destroy the enemy castle.

Minuses : People cannot build. Catapults & Rams are the only things that can destroy buildings.
WWII :
Classes: Soldiers,Medic,Anti-tank troops,Builder,sniper,assasins.
New stuff : Many of the general WWII weapons ( Panzer,Gewrer 43,Knife,Grenades,Mp40,Sten,Ruger & LOTS of more )
VECHICLES! :D : Tanks,Airplanes,Little Jeeps.
Missions:
A)Take the Documents & return them to your base ( Like right now :P )
B) Assault
C) King Of the Hill.
Terrain: Berlin,France,England...

Modern:
Classes Soldiers,Medics,Builders,Snipers,Spies & LOTS of more...
Weapons : Many of the Modern weapons
Vechicles : Many of the Modern Vechicles
Terrain:Apocaliptic Modern city ( City Ruins )
Objectives :
A) Assault
B) Hunted - the team must secure your VIP/hostage to safety,DO NOT LET THE OPPONENT KILL HIM!
C) CTI - Capture the Intel
D) King Of the Hill.

But,those will be seperate 2 Addons. When Installed,you can choose between those. the WWII is the base,so you won't need to download & install it - just install the game.
When installed,you will need to select which Style you want ( NOTE: For every style there are custom servers ( You can't play in a Medieval server with Modern;WWII stuff )
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Pistols & Knifes;
Achievements;
MILESTONES ( Earn amount of achievements & you get something special you can use )
Inventory; Backpack ( This makes you sure you selected the right equipment )