This game should have challenges like in COD Modern Warfare 2 that make your climb the ranks faster than killing people. The challenges should increase your rank by difficulty, harder ones make you get closer to being promoted, easier ones make you get closer by little.
Create a feature vote for it. You'll need to explain that in greater detail though. Like:
- Whats the highest rank?
- What happens when you get to the highest rank? New gun? New game? Emblem? Unlockables?
- Who determines what the challenges are
- What would the challenges be? Kill 100 people with a Carbine? (Baring in mind this
could encourage spawn camping again...)
Personally, I think rewards are a good idea. But for your K/D ratio in a game, you get rewarded points. So if you have a K/D ratio of 0.71 you get 71 points. If you have a ratio of 3.56 you get 356 points - with the highest ratio possible being 5.00 (500 points), then, once you've collaborated a sufficient amount of points you can buy an extra grenade, buy a new gun? etc. etc... But this could be getting to much based on Cod..