Tower defense games are built around controlling space and timing by choosing where to place defensive units and how to upgrade them. Enemies typically move along predefined routes, and players must prevent them from reaching a target by using a limited number of placements and resources.
Most tower defense games follow a wave structure, where each wave introduces stronger or more varied enemy types. As difficulty increases, players may need to adjust strategies by mixing different towers and upgrading key units.
Upgrades and progression systems can vary between titles. Some games keep progression within individual levels, while others include long-term upgrades that carry across stages.
Tower defense games are often suitable for short play sessions, but many include campaigns, challenge modes, or replayable levels for longer-term play.