Killzone: Shadow Fall, the latest entry in Guerrilla Games' series about shooting anyone with glowing red eyes, has sold over 2.1 million copies worldwide. That figure accounts for physical Blu-ray discs and downloads sold through the PlayStation Store.

The 2.1 million milestone was achieved on January 15, Sony says. To put that into perspective, Killzone 2 took nearly seven weeks to reach one million in sales. Though we're missing exact figures, we know Killzone 3 debuted at the number eight spot in the February 2011 NPD charts.

Killzone: Shadow Fall is set on the planet Vekta, where both the Helghan and the ISA reside. Players take up the role of Lucas Kellan, a covert assassin and espionage agent. Kellan works behind the scenes under the orders of ISA Shadow Marshal director Thomas Sinclair, a man who seemingly views the Helghan as animals more than the gun fodder our review suggests they are.