They Eat the Walls

'They Eat the Walls' is a short tower defense game where the level itself is edible.
They don't go around
A rat weighs the walk around your defences against the walk straight through them. When going around takes too long, it stops and starts chewing. Wood, stone, packed mud - all of it is food. Only bedrock holds.

An endless horde of rats
Hundreds of thousands of them, boiling up out of the deeps. You've nine kinds of cannon on the gallery, seven things to drop down the shaft after them.

Build, then hold
Between waves the cave stands still. Lay wood, set stone, drag out cannon emplacements, take as long as you like. Then you start it, and the dark fills up.

You are not meant to clear the cave. You are meant to still be there when it ends.

Features
Walls that cost, not block - rats path through anything when going around takes too long, then stop and chew their way in

Hundreds of thousands of rats on screen at once, pathing individually

Nine cannons - rapid-fire, mortars, flame, frost, chain lightning, and beams that ricochet off the cave itself

Seven abilities on cooldown, including a lure that pulls the horde somewhere else entirely

Different building materials - cheap wood that goes fast, stone that holds, and the difference between them decides where they break through

Different kinds of rat - including one that chews six times faster and one you really don't want reaching you