MAZESTORM

You don't follow a path, you build one. Enemies always take the shortest route from the rift at the top to your gate at the bottom, so every wall you place makes their walk longer and gives your towers more time to shoot. Sealing the route completely isn't allowed — a gap always has to remain.

Five chapters of eight levels each: Frostmaw, Mire of the Drowned, Ashen Cauldron, Sand Graves, The Rift. Each has its own terrain rules — ice that speeds enemies up, mire that sinks your buildings, erupting lava channels, sandstorms that cut tower range, and enemies that heal one another. Fliers ignore the maze entirely; burrowers tunnel underneath it.