Compare where enemies escape before spending your next coins. An upgrade helps an existing firing position; a new tower can cover a stretch where your current defenses cannot attack.
Count useful firing time
Suppose an upgrade adds ten damage per second for three seconds of contact: that is about thirty extra damage. A new tower dealing eight per second for five seconds could add forty. These are illustrative numbers, not the linked games' statistics. Range, armor, target priority and splash damage can change the result. Judge the next wave and the actual path instead of buying the largest displayed number.
Try the steps
- Watch the point where a surviving enemy leaves your defenses.
- Compare an upgrade's added damage with a new tower's reachable path and cost.
- Buy one change, then observe whether fewer enemies escape at that point.
Is a new tower always better coverage?
No. A poor location may barely reach the path, and spreading damage may leave every enemy alive. Check the game's placement and upgrade rules, then concentrate enough damage to finish targets.
