HvZ is about being fun for both sides. Having it Cod zombies style would be like late game hvz where there's only a few humans left with everyone else a zombie. Those don't last very long. The difference is that the last few humans in that case actually had to survive long enough ...
On one multiplayer map titled "Streets", zombies will appear halfway threw and swarm the winning team, providing more of a challenge. Some levels recquire the player to roam freely around city centers to spy on hostile or neutral countries. Space battles are also present in the campaign, ...