How to make Midis sound more... real?

[steerpike]

If you want your MIDIs to stay within your game as MIDI files, then soundfonts are the way to go. If I understand sound setups correctly, though, that'll only work on your own system or for someone who's also set up with soundfonts.

You could import your MIDIs into a sequencer and play or export them using a virtual instrument. The exported files won't be MIDIs - they'll be WAVs, MP3s or OGGs - but they'll sound a lot better.