Use main route to solve one real in-game task.
When a wave breaks through, watch the first weak lane, strengthen the unit that was supposed to hold it, and replay the same plan once more. The best fix is the one that changes the next wave, not every slot on the board.
- Roll until the wave is stable.
- Place until the wave is stable.
- Defend until the wave is stable.
- Upgrade until the wave is stable.