2 teaser was shown behind closed doors, and was never released to the public. It featured various battles, destructible environments, and lighting effects among others. Killzone 2 was shown to a panel of journalists at a special pre-E3 2007 event in Culver City, California, and then the next day to the public at Sony's E3 press conference. An in-game trailer showing real-time gameplay of Killzone 2 was also released, along with several videos of extended gameplay. A number of media outlets since E3, such as the BBC, have referred to Killzone 2 as being "one of the most cinematic and immersive games ever produced on a console". At the Leipzig Games Convention in 2007, Killzone 2 was presented in playable form to the media. It was the same demo level as shown at E3 2007, although journalists were allowed to play it hands-on. At Sony's PlayStation Day 2008, the first level in Killzone 2s single-player campaign was presented, named "Corinth River". Michal Valient, a Senior Programmer at Guerrilla Games, presented details of their Killzone 2 proprietary game engine at a Developers Conference in July 2007. As with many other titles published by SCE, including LittleBigPlanet and Infamous, Killzone 2 uses a deferred shading engine which enables far greater control over the game's characteristic lighting palette, while maximising processor throughput and limiting shader complexity. Other games to use similar approaches include Rockstar Games' Grand Theft Auto IV and GSC Game World's S.T.A.L.K.E.R.: Shadow of Chernobyl. However, this approach does create some additional problems, notably with respect to anti-aliasing and transparencies. The former was solved using a MSAA Quincunx (multisample anti-aliasing) solution, and the latter by the addition of a standard forward rendering path. The game's graphics were universally praised by critics. The animation was done in Maya 8.5 with some motion capture animations tweaked in MotionBuilder. 3D artists, animators and level designers used Maya as their production environment, which is unusual considering that most 3D games are produced using 3ds max. A large library of custom Maya tools and scripts was created to support these different disciplines. Tools like "Hyperion", a lightmap rendering software, were used in place of Maya's viewport rendering software. In-game animation was assisted with another tool they created called "AnimationBlender" and particle effects were edited using a tool called "Particle Editor". They also created a tool called "ColorTweaker", which gave them the possibility to do color correction