Overview
Four Days: World Defense Guide
There are 9 tower types in the game, each with their own unique effects and abilities. All tower types are already unlocked at the start of the game; you don't need to unlock them by completing various stages or buying them. The game features a diverse selection of towers which allows players to a lot of strategic possibilities. Each tower can be upgraded up to three times to increase their power and range.
They can be upgraded within the game by spending the resources. Off-battle, you can upgrade them permanently by using Tech Points which you can earn by completing missions and defeating Research Waves that will appear during battle. Spending Tech Points to upgrade these towers will allow them to have additional effects as well. Take note that while upgrading in the middle of a mission, the selected tower will be disabled and disappear for a few seconds to complete the upgrade.
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