When to save and when to upgrade a tower

The usual mistake in defense games is not placing a tower badly, it is upgrading too early, before the heavy wave.

The usual mistake in defense games is not placing a tower badly, it is upgrading too early. Every coin that goes into an upgrade on wave two is a coin that is not available for a new tower on wave five, and wave five usually takes a different route.

A rule of thumb that holds up: do not upgrade anything while there is still an empty slot on the main path. An extra tower adds coverage, while an upgrade only adds damage to ground you already cover. Coverage first, power second.

Saving only makes sense when the next wave brings something your basic towers cannot touch, or when the map narrows and there are no useful slots left. At that point, pooling coins into one high-tier tower beats spreading them across five small upgrades. Read the next wave before you spend, not after.

How to read the next wave without opening a menu: look at the unit type walking in front. Armoured units usually arrive slower, and the wave that brings them is always preceded by one fast wave designed to drain your coins.

If you have already spent everything, do not add towers mid-path. Add them at the last corner, where a tower gets the longest firing window before a unit leaves its range.