Read more about Helghast at: Wikipedia

Official Site: Sony

Killzone is a series of shooter games exclusively for Sony Computer Entertainment's (SCE) video game consoles. The series is developed by Guerilla Games, a subsidiary of SCE. Killlzone consists of four games for the PlayStation 2, the PlayStation Portable, Playstation Vita and the PlayStation 3 respectively. The series began on the PlayStation 2 in November with Killzone, and continued on the PlayStation Portable in October with Killzone: Liberation and then again on the PlayStation 3 in February and also an upcoming Vita game. The most recent installment is Killzone 3, released in February for the PlayStation 3.

The series is about the war between the Interplanetary Strategic Alliance (ISA) and the Helghast. The protagonist of the series are Cpt/Col. Jan Templar (Killzone and Killzone: Liberation) and Sgt. Tomas "Sev" Sevchenko (Killzone 2 and Killzone 3), while the main antagonist is Helghast Emperor Scolar Visari; his death in Killzone 2 brought about the rise of two new antagonists and the hopeful heirs to Visari's throne, Jorhan Stahl and Admiral Orlock in Killzone 3. The Killzone series follows the continuous war between the ISA and Helghast taking place on both ISA Earth colonies and the planet Helghan, the home planet of the Helghast.

Killzone, Killzone 2, and Killzone 3 are first-person shooter. Killzone: Liberation is presented as a third-person shooter and is the only of that kind in the series to date. All games were developed by Guerilla Games and published by Sony.

Players in the series can only carry two different weapons at any given time. Players can either obtain ammo or swap out their current weapons with any weapon dropped by a downed foe or from those scattered around the various maps. In Killzone 3, players can carry up to three weapons, with the third weapon spot reserved for heavy weapons (e.g. machine gun, rocket launcher, etc.).

Helghast has not been a contender in any CBUB matches.