IMO CoD 2 3 looked the same. so did 4 5 and 6. Weapons an vehicles are changed in each game just like they are in cod. Halo 2 and Halo 3 were VERY different. Halo 3 got forge and ODST added in firefight and Reach has both and they are much better now. only cod 5 offered a new mode, nazi zombies...