It is possible to play chiptunes using an Arduino Nano without additional shields, simply adding a Digital to Analog Converter (DAC) built using resistors. VERSION EN ESPAÑOL
Chiptunes must be in MOD, S3M, XT or IT format. They have to be converted to a format named Profundic Music File (PMF) by its creator Jarkko Lempiainen. It's a kind of compressed and simplified format to be incorporated in Arduino projects
Using pmf_converter.exe tool, the aforementioned audio formats can be converted to FLASH constant data for Arduino!
In every entry of the blog, there is a video of a different chiptune, also a downloadable file with the arduino source code, schematic, and the original tune!