From Creatures Wikia
MNGPlayer is a program written by GreenReaper for playing the MNG music for Creatures 2, Creatures 3 and Docking Station. This music can be created and edited in its sister program, MNGPad - these are packaged together as part of the MNGEdit project. It requires the .NET Framework from Windows Update to be installed first.
Source code from MNGPlayer (which is freely available for download under the GPL) can be adapted or derived to add MNG support to other projects.