One new blocks should be barbed wire. you place it, and people of the opposing team are hurt if they touch it. Buy barbed wire can be destroyed by grenades and grenades only, or a turret, artillery strike, or any other explosive devices.

You should also implement turrets, where you sit in them and aim with your mouse. it fires semiautomatic explosive rounds, or fully automatic light bullets. They can only be destroyed by 60-90 rounds of a rifle, or 3 grenades at pointblank range, or 3 hits of any other explosive meterial.

Artillery is also a god additive. you must get a killstreak of 7 or more to get it. You fires a tracer round into the general area you want it to be in, and explosives come raining down around that area.

Killstreaks and achivements would also be nice. Also customizable weapons, classes, and field medics.

Another thing can be a machine gun. It has 3 belts of 100 rounds each, but you walk slower carrying it, and can only fire it without moving.

Also, adding an official sniper rifle would be good, instead of an infantry rifle. it has a better scope, but you can only fire it through the scope while staying still. It should have 4 clips of 5 rounds each and can cut through blocks in one blast.