5. The Unlocks
So many unlocks. For starters, there is the four classes. Then, within each class is all the class specific unlocks like guns and gadgets. Then, there is 20 or so unlocks for each gun. And then there's vehicle unlocks, ranks and so much more. There is seemingly an endless stream of stuff to collect, and the satisfying sound of unlocking something makes it all worth it. Oh, the sound. So good. Experimenting with all this gear is fun too, trying to change a weapon or class' playstyle to find something truly unique and something you. Which brings me to my next point....