Vertical shaft tower defense: enemies dive down from the surface toward the core; elevator-car turret platforms travel between ring stations, and you rewire which car goes where. Signature: ride the car to intercept a breach on the deep rings.
Industrial shaft steel, cable and pulley shadows, ring-station warm lights against cold depths.
Click, Enter or Space to start. Place and upgrade towers with the mouse and number keys, or by tapping on touch, to stop each enemy wave before it reaches your goal. The HUD tracks lives, cash and wave.