Click on buildable spots to open the tower menu and select a type. Confirm to place; the cost deducts from your gold. Towers attack automatically within their range as enemies pass.
Earn gold from each kill, and use it for new towers or upgrading existing ones (click an existing tower to see upgrade options). Survive all waves without too many enemies reaching your base.
Build for the Next Three Waves - Don't optimize for the current enemy mix; the wave after the next is what your towers need to handle.
Slow Towers Pay for Themselves - A single slow tower at the front of a path can double the effective damage of every tower behind it.
Don't Spread Too Thin - Two well-upgraded towers in a critical position beat eight weak towers scattered randomly; concentration usually wins.
Watch the Enemy Composition - Each wave's enemy mix telegraphs what you should counter; armored waves want magic, swarm waves want splash, fast waves want slow.
Keep an Emergency Reserve - The hardest waves often surprise you; having 50-100 gold spare for a last-second tower has saved many runs.
