Upgrade or build more? The choice that decides your run

Every tower defence run comes down to a quiet decision you make dozens of times: pour coins into upgrading a strong tower, or spread out and build another. Most players build too much and upgrade too little.

Damage usually scales harder than coverage. A single high level tower in a good spot often out damages two mid level ones, and it does not split enemy attention. If your kill zone is holding but slipping, upgrade before you expand.

The exception is enemy variety. When waves mix armour, speed, and flying types, one specialist cannot cover everything. That is when a second, different tower earns its place. Read the upcoming wave if the game shows it.

A simple habit helps: after each wave, ask whether anything leaked. If enemies slipped through, find out why and fix that exact gap rather than blanket building. Targeted fixes win runs.