For those not in the know,
wikipedia wrote:A chiptune, or chip music, is music written in sound formats where all the sounds are synthesized in realtime by a computer or video game console sound chip, instead of using sample-based synthesis. The "golden age" of chiptunes was the mid 1980s to early 1990s, when such sound chips were the most common method for creating music on computers. Chiptunes are closely related to video game music, which often featured chiptunes out of necessity. The term has also been recently applied to more recent compositions that attempt to recreate the chiptune sound for purely aesthetic reasons, albeit with more complex technology.
So chiptune is basically music made with oldschool videogame software/hardware to sound like oldschool videogame music.
A good place to look this stuff up would be 8-bit collective which has an abundance of excellent chiptune composers. Artists like FTFX and Sabrepulse