- A burrower is tunnelling, unseen, toward your colony on the bottom row. It moves one step every turn.
- Each turn, drop one card: tap it, tap the board to aim, tap again. Tap the card again to rotate.
- Pieces become walls. The number on a piece is how far it was from the burrower when you dropped it.
- Walls that shake are touching it right now. Walls crumble after 6 turns.
- Drop a piece on top of it to hurt it. Or wall it into a pocket of 3 cells or less to trap it.
- Fill a whole row and it clears like Tetris, giving you a free move. So you can't just wall off a line.
- It gnaws through walls slowly. If it reaches the colony it takes a colonist. Lose all 3 and it's over.
- Lure pulls it toward bait; Echo updates every number for free; Spike does double damage.