Dungeon Defenders is a tower defense variant with action elements. Just like in every tower defense game, the goal is to fend off enemy waves by building up defense mechanisms during fight pauses. However, in this game there are four people building up said constructions at once and the whole game is played from the over-the-shoulder perspective. During the waves players actively fight against the monsters, hence the action elements.
Of course the construction costs money which is found at slain enemies or in treasure chests in the levels. Besides money there are also weapons, items and armor to find which boost the player's stats - along with experience points and level ups. However, there is no reward system for teamwork and item division works after the "first come, first serve" system. Every player has the choice between four classes with different abilities. The game is primarily meant to be played co-operative with other players, but there is also a story mode in which children fight off evil forces.