Firmware Version 2.2 introduces several new feedback modes.
Use Recycle mode to create arpeggiator, shimmer, or organ sounds, or Post Delay mode for clouds of detuned, randomly panned grains. Try different Repeat modes for random rhythmic stutters, CD skips, and glitch sounds.
The feedback mode can be set using the web editor (as shown here) or MIDI. The setting is stored in presets and remembered when power is off.
Web Editor:
https://www.redpandalab.com/content/apps/particle-editor/index.html#/
Owner's Manual:
https://www.redpandalab.com/content/docs/Particle%202%20Owners%20Manual.pdf