When you launch this program, it will ask you for a path to a folder with stems in it. These files must be in wav, flac, or MP3. The sample rate or channel count does not matter.

Keys.
Tab and shift Tab: Move through loaded stems
M: Toggle Mute the focused stem
S: Toggle Solo the focused stem
R: Randomize track positions.
U: Unmute all stems.
I and K: Change volume of either the master mix if controlling yourself, or the selected stem if controlling stems.
v: toggle if you move your position or the selected stem's position.
Arrows: Move yourself or a stem.
Page up and down: change reverb level
J and L: change reverb time
Home and End: Change reverb mean free path
left and right brackets: Change the pitch up and down 1 semitone.
backslash: reset pitch to default.
Space: Pause/resume
Enter: Restart from the top.

Enjoy!