In time line, Killzone 2 follows Killzone: Liberation, and Killzone, and appears to take place entirely on Helghan, the home-world of the Helghast who invaded an Interstellar Strategic Alliance (ISA) colony in previous Killzone installments. Two years after the Helghast assault on Vekta, the ISA is taking the fight to the enemy's home world of Helghan.