Software like OpenMPT or Renoise loads SoundFonts directly. OmegaGMGS2 provides "fake" real instruments that sit well alongside SID chip or NES waves.
The slightly gritty, early-2000s ROMpler aesthetic of OmegaGMGS2 is perfect for Lo-Fi. Resample the "Electric Piano 1" (Rhodes) through a VHS tape emulator, layer the "Analog Drum Kit" with a record crackle, and you have an atmospheric beat in minutes—no expensive vinyl sample pack required. omegagmgs2 soundfont
If you are playing a web-based MIDI game: Software like OpenMPT or Renoise loads SoundFonts directly