Killzone 2: Why would anyone want to invade Helghast?

[Munkeh111]

1. The levels look similar because we have seen about 2 levels!!!!
2. If you want backstory, then go to Killzone.com and there is a ton of back story, I spent at least 1 hour going through it. It starts from the first colonisation of off-world colonies and the influence of the Helghan Corporation