klystrack is a tracker for making C64/NES/Amiga-style chiptunes on a modern platform. Here are some features:

• 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)