Sound
    Additive synthesis with filters (think SID, Atari, NES etc.)
    Hard sync and ring modulation (like SID)
    FM synthesis (think Adlib, MSX, OPL2 etc.)
    Wavetable for samples or custom waveforms to be used in synthesis (think Amiga, SNES)
    Built-in wave generator and editor
    Programmable instruments not limited to simple arpeggios
Sequencer
    Tracker with free positioning of patterns
    Pattern transpose
    Pattern length is not fixed
    Hard limit of 32 channels but this can be raised (just ask if you need more... sounds crazy, though)
    Fully themeable, includes half dozen themes
Effects
    Stereo chorus
    SNES-style multitap echo
    Bit crusher/decimator
Export
    Own custom format with a tiny playback library to be used in games, demos etc.
    Export as .WAV
    Export each track as separate .WAV's
    Export wavetable items as .WAV's (use klystrack to create one-cycle waveforms)
Import
    Import .WAV's to use as samples
    Import Protracker and FT2 modules
    Import C64 SID files (Rob Hubbard player)