In 2001, Bohemia Interactive Studio and Codemasters released Operation Flashpoint: Coldwar Crisis. Touted as a tactical shooter/battlefield simulator, it garnered critical acclaim for it's realism and artificial intelligence, largely due to its use of the Real Virtuality engine, which at the time was also being used by the military combat simulator VBS1. An Xbox port of the game was released on the Xbox in 2005. Several expansion packs followed the original release, but, due to a falling out between developer Bohemia Interactive Studio and producer Codemasters, a true sequel was delayed. Codemasters, acting as both developer and producer, recently released Operation Flashpoint: Dragon Rising (OFP:DR).