The Eden editor is ArmA 3's built-in 3D scenario editor. It includes the ability to place almost all objects in the game (excluding roads and most plants) and to create missions with triggers or SQF scripts. The Eden editor replaces the 2D editor used in previous versions of ArmA, including older versions of ArmA 3.
Units can be given waypoints to create patrols or incoming attack forces, as well as to give players objectives to complete. Units can also be edited, including altering their gear, their skill level, which groups they're in, and what stance they will be in at game start (e.g. prone, crouched, etc.) Groups can be edited to set their combat state (careless, alert, etc.) as well as their formation and speed mode.
Containers and vehicles can be edited to provide different equipment. Many vehicles also have options to edit their appearance and most aircraft offer dynamic loadouts which allows their available weapons to be changed before the scenario is launched.
Scenarios can be uploaded on the Steam workshop to share with the ArmA community, and can also be accessed when running a server in multiplayer to play with friends.