It follows that your choice of SoundFont can have a noticeable impact on your classic video game experience. To put it simply, a SoundFont is a library of instrumental sound samples, instructions and parameters which, when loaded by a compatible synthesizer (either implemented in hardware or in software), will dramatically change the sound of MIDI output.
MIDI doesn't have any sound information in it per se, therefore the quality of the samples utilized by your MIDI synthesizer determines the quality of your MIDI sound as much as the composition itself. The digital equivalent of sheet music, MIDI was commonly utilized by the video games of yesterday.
TL DR: After sitting on it for something like a decade and a half, I'm releasing my General MIDI SoundFont to the public.