Three NBA 2K games were released for the Sega Dreamcast: NBA 2K, NBA 2K1, and NBA 2K2.
The series began as a Dreamcast showcase in 1999, when Visual Concepts developed NBA 2K and Sega published it as a launch-era basketball simulation. NBA 2K1 followed in 2000, adding online play and new street-basketball and management features. NBA 2K2 arrived in 2001 and expanded the series to PlayStation 2, Xbox, and GameCube as well as Dreamcast.
NBA 2K2 was the final NBA 2K release for Sega's console. That makes the count three, not four: NBA 2K3 debuted on PlayStation 2, Xbox, and GameCube, leaving the Dreamcast behind. A common mix-up comes from counting later Sega-branded basketball games, such as ESPN NBA Basketball, as NBA 2K entries; they are related successors but are not numbered Dreamcast releases in the NBA 2K run.