Two maps. The Meadow is the open classic. Boulder Hollow puts the gates in opposite corners with stone spines you must wind around, and its flyers cut straight across the diagonal (the faint dashed line). The Keep hides the exit inside a ring of stone with one door on the far side, so every route circles it first. Pick a map whenever you start a new run.

Build a maze. Enemies walk from the spawn gate to the exit gate along the shortest open path. Every tower you place is a wall, so shape a long winding route and line it with firepower.

Place: drag a tower from the palette onto the board, or tap it and then tap a cell. The ghost shows range and the dotted line shows the new enemy path. You can never fully block the path.

Tap a tower to upgrade or sell it (70% back). Drag a placed tower to move it, even mid-wave: moves are free, keep the level, and reroute enemies on the spot. You cannot drop onto an enemy or seal one in.

Waves come on a countdown, or send early for bonus money. They can overlap. Every 50th wave brings a boss.

Perks: every 8th wave you clear offers a choice of three run-wide perks (range, fire rate, damage, cheaper building, interest, extra lives, and more). Pick one; it lasts the whole run and some stack. Everything on the board freezes until you choose, so take your time.

Combos: kills within 1.2 s of each other build a multiplier up to ×5. Fast, efficient kills score far more than slow ones.

Flyers ignore your maze and fly straight across. Every tower can hit them, but Cannon, Flame, and Poison do half damage to them and Missiles do double. Each tower's popover lists what it is strong and weak against.

Shields (from wave 8) block the first four hits outright, whatever their size, so fast weak shooters strip them best. Burn and poison seep through. Splitters (from wave 9) burst into three swarmlings when killed, right where they died.

Undo: the ↶ button takes back your latest placement at full price (level-1 towers only). Selecting a wall also offers "Sell all walls" for fast maze reshaping.

Your run is saved automatically if you close or background the app.

Keyboard: Q W E R T Y U I O P A B C D F G pick towers in palette order · click to place · Esc cancels · Space pauses · 1 2 4 set speed · N or Enter sends the next wave · U upgrades and S sells the selected tower · Z undoes the last placement.