MAMPlayer, or Music Animation Machine MIDI Player, is (or is at least one of) the earliest MIDI Player(s) which was thought up by Stephen Malinowski in 1974. The very first version was made in 1985, the first private release in 1988, and the first public release on 11th June 2006. It has been a long time since it was last updated, the latest release being from 18th August 2006, which is probably the reason why it isn't very good at playing large MIDIs. Despite this, it looks good visually, and one can choose for the notes to be coloured by either track or tonality. The program has had only 34 updates since it was first released publicly, all within a few months of each other. The program is used the most by TrollfacepalmAcer78.
It is unique in the sense that it has twelve different display modes, which all have their own use and look very different. They are, in order: pitch bars, circle of fifths colour wheel, interval types wheel, interval types + pitch bars, shapes, harmonic staff, harmonic compass, harmonic compass + pitch bars, triads, part sequence, part motion, part trajectory. Some modes lag less than others due to having to display less. As with most other MIDI Players, this is a 32-bit program, so it is recommended to use the 4GB Patch on it.
The program has its own file format, the *.mamx file. There are six MAMX files of classical pieces available to download off the MAM Player Page. There does not seem to be any kind of MAMX file editor or any other MAMX files.