Hold the road for 20 waves. A boss marches in every 5th wave.
Enemies march along the sandy road toward your castle. Pick a tower, then tap a patch of grass next to the road to build it. Tap a tower you built to upgrade it or sell it. Arrow towers are fast, frost towers slow enemies down, and cannons hit a whole group. Stop every wave before it reaches the castle. If you clear a wave without letting anyone through, your streak grows. Keys: 1, 2 and 3 pick towers, N sends the next wave, U upgrades and S sells.
Compare a spot before spending gold. Columns run left to right; rows run top to bottom.
Road · outlined road tiles are in range · P planned · T built
Coverage counts road tile centers. It does not predict kills or slow effects.