In 2006 a climatic catastrophe triggered a new ice age on earth. A hundred years later, everyone gave up on finding a solution to the problem and two superpowers were formed: Europe and on the other side the Pan Asian Coalition - causing an arms race. Now it's 2142 and the war for the few resources left has already been going on for a few years, with no end in sight.
Besides the now futuristic setting, the main changes to Battlefield 2 are the new Titan Mode and the revised character and stats system.
In the Titan Mode your goal is to bring down the enemy Titan, a giant ship flying high above the battlefield. At the beginning of the round, the ship is protected by a shield which the enemy team needs to take out. To do so, they can either fire everything they got on it or simply gain control over the missile silos scattered over the map. Once a missile silo has been acquired, it continuously fires missiles at the enemy Titan. Once the shield is down, the players have to destroy three stations inside the ship so that they can gain access to the central core and destroy it.
The armory and vehicles are similar to Battlefield 2, but they look more futuristic. There are a few additions and changes. The number of character classes has been reduced to 4, but you can customize them with many items and weapons unlock-able during the course of the game. This way, you can provide your scout some C4 (which is now called RDX) and turn him to an special ops. The assault, on the other hand, can be equipped with a defibrillator.
The whole stats system has been reworked too. There is now much more to gain and the advancements happen more quickly. You can retrieve the dog tag of killed enemies with a knife and look at your collection on the stats page.