Build a maze with towers and walls, but always leave at least one route from the enemy entry to your base.
Select a tower, wall, or support action from the build panel.
Move the pointer over the battlefield to preview the selected placement.
Click an empty tile to place the selected defense if the route stays open.
Click an existing defense to open upgrade and sell actions.
Select a tower, wall, or support action from the build panel.
Press and hold on the battlefield until the placement preview appears.
Slide while holding to choose the tile, then release to place.
Drag before the preview to pan across the battlefield.