Richi_S has created a basic sound engine for the Atari 2600; posted at AtariAge forums.  Comparing IGSE to Paul Slocum’s Music Kit 2, they are pretty far and in between one another.

IGSE features volume or pitch enveloped “Special Instruments.”  Music Kit 2 does not support full control of volume; but you can control slight increments of the instrument’s attenuation.  INGE is based on manipulating the frequency and volume of a single instrument on both channels.  Whereas Music Kit 2 is based on modulating all of the available instruments in sequence, and the frequencies of those instruments while only slightly shifting the attenuation of the instrument up or down for emphasis.

INGE as its acronym clearly states, is best used for an in game sound engine due to its limitation of not being able to switch up instruments “easily” and quickly; such as supported by Music Kit 2.

Hopefully more features and capabilities will be added to INGE; since Richi_S appears to be a motivated, positive and focused anachroprogrammer. :)