Download copy items
(Drag and drop downloaded file onto canvas to restore)

Drag things around with the mouse
Hold c, click and drag, then release click - copy
u - undo
r - redo
p - pause/unpause
s - step (while paused)

Object shortcuts:
w - white piece, can be pushed by fans
b - black piece, solid wall
f - fan arrow keys - directional fans, airflow can be blocked