Here is my list.
- customizable looks (glasses, berrets, turbans, jackets, ghillies etc.), but that it would still be fitting in the according army - no rainbows
- rewards for badges - for ex. if you got the Basic Assault Badge, you get a magazine of armor piercing bullets as a bonus, but no attachments as rewards, I will explain it later
- lots of buildings with rooms etc. You could find attachments, bandages and first aid kits - the kits will only be available for use by a medic, but a regular soldier could carry them and give them to a medic aswell (explained in the next point),ammo and grenades, plus maybe some weapons (like in the house of redneck you could find a sawed-off shotgun) (flash/stun/smoke/gas etc.), it would be randomly set at the start of the map, to prevent sprinting to one known stash
- healing - everyone would have 2 bandages (could be found in buildings) and they would heal slowly, but atleast something. Only medic would be able to use First Aid Kits that heal considerably faster, but are much rarer (they would be issued with 2 kits/1 bandage). The max would be 4 found bandages and 2 kits.
- before you spawn, you could choose between 3 options - Most ammo, less grenades - 5 mags (+bonus ammo if you got the badges) and 2 nades
ammo and grenades - 3 mags 4 nades
low ammo and most grenades - 1 mag 5 nades
- sidearms are another story - the MEC (or whatever the super-bad-weapons-of-mass-destruction-owners would be) could start with Makarov PM and the NATO could start with M1911/Beretta 92FS, you could unlock Desert Eagle, MP7 and various other pistols
- unlocks - plenty of side arms, carbines, assault rifles etc. They could be unlocked liberally as you wish, but they would only fit to a certain class (Sniper Rifles - Snipers etc.)
- customizable classes (not to the point of CoD4) but I mean like add whatever weapon you unlocked
- no ammo camos, they are lame, except maybe a ghillied sniper rifle
- bigger maps that offer both urban and outside fights - you could have a small vilage with big plains around it where tank battles could take place, while the urban setting of the village will offer nice fights in the barns etc.
- vehicles - you could take control of vehicles you find - cars, tractors and other mobile stuff.
- vehicles would also be subject to fuel/ammo - ammo would have to be replenished by APCs, regardless of any support guys. For fuel, you could get it from tapping stations or some well in the HQ
- removal of ammo replenishing by support fellas - let them have a tear gas launcher instead like in SF
That is all for now, I will add if I can think of something else.