My friend asked me to make something like this for him.
What it is:
More or less a mixer of 2 effect loops. One loop has the volume control at the effect send and one loop has the volume control after the return. The x-axis of the stick controls one loop and y-axis the other.
Also each channel can be subjected to a feedback loop, which makes it behave a bit like the "total sonic annihilation" pedal (per loop).