You are looking at the 3D sensor of a 4D hypercamera.
WASD: Move camera forwards, sideways
Q/E: Move camera in ana, kata directions
IJKL: Rotate camera up/down, left/right
U/O: Rotate camera in wx plane
Y/P: Rotate camera in wy plane
Mouse drag: Rotate sensor view
Mouse wheel: Zoom
Click: Select vertex
Selected: None