Timed geysers erupt on schedules that damage anything standing over them; you build firing platforms between cones and bait enemies into vent windows. Signature: a perfect volley of five eruptions on the ogre column.
Yellowstone ochres and turquoise sinter terraces, steam plumes, mineral-spring gradients, sun-halo mist.
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.