From the builder:

Grimrobe is cascaded gain stages design including LM386 power amp to create rich distortion, which covers massive range from soft clipping drive, thru robust overload of integrated circuits to clangy octave mayhem. Complex 'MORE' channel operation is the prime purpose of Grimrobe project, but its switching layout includes also simpler and familiar rodent type distortion. Flexible EQ section, multiple voices and ability to power it with 18V for increased headroom make this pedal an extremely versatile gain provider for all your heavy music demands.

CONTROLS:
Full manual at bottom of the page.

VOLUME - output level (pedal can get really loud at high gain and LIMIT off position)
HIGH - treble cut/boost
LOW - bass cut/boost
HARMONICS (rotary switch) - selects circuit type within channel 'MORE'
MORE knob - gain of channel 'MORE'
DISTORTION - gain of input amp

VOICE switch - sets overall character of channel 'MORE' - left setting is high gain with full frequency range; center setting is low gain with gentle bass cut; right setting is high gain with emphasised midrange
LIMIT switch - hard clipping diodes 'after' both channels - left setting uses silicon diodes; center setting is off; right setting uses LEDs
COMP switch - allows to engage soft clipping diodes in the input amp - left setting uses silicon diodes; center setting is off; right setting uses LEDs

MORE footswitch - engages 'MORE' channel with additional LM386 power amp stage before LIMIT and EQ universal settings.