A variant of an old classic puzzler, but with tiles instead of landscapes. A playable version can be found here (very out of date - try the release)
To move the camera, either right-click and drag the screen, use the WASD keys or left-click the minimap.
Q and E: Select ONLY lemmings going either left or right
P or Space Bar: Toggle pause
F: Toggle fast forward
G: Toggle grid
B: Go back in time (1 frame)
N: Go forward in time (1 frame)
WASD or Right Mouse button and drag: Scroll camera