I think it's important to mention to people that think there should be this survival mode with zombies poop that this should not be a CoD side-shooter, in fact, that would ruin the game. It should be it's own style without all this rank systems and weapon attachments malarkey people apparently want. Seriously, go play Call of Duty. Ranking creates an imbalance between players, especially for multiplayer. The weapon purchasing system in Raze 2 is more than enough to fulfill that.
However, there should be a world war between humans as well as the aliens assaulting Earth. This could add another campaign people are looking for, creating an even harder difficulty. Rocket launchers should be less available, and Rifles very common. For vehicles, there should be a tank, a lighter recon vehicle, and some aerial vehicle.
For this new campaign there should be crazily insane people tampering with the knowledge and power of alien technology. this would not only draw human interest towards facilities but alien alert in research against them. In this would be introduced some assault mode, where command points must be taken or defended in a certain, progressing order. A time limit or casualty limit should be put as a victory condition.
There is much that can be done to improve Raze as it stands, but we, the players, can only wait for releases. Even something as simple as patches cn fix the game.