Drop props from the core pack, the shared library or your own uploads. Add point, spot and directional lights. Place spawn markers and trigger zones that your rules can hear.
Draw walls, panels, rooms and stairs on as many floors as you need. The runtime derives walkable space and collision from what you drew, so there is no separate collision pass.
Every parameter is typed and validated as you type. Select a light and you get intensity, range and colour. Select a trigger and you get its kind, size and the zone id your Logic rules match on.
Preview runs the same runtime a published game uses, with your HUD, audio, rules and camera choice. Escape returns you to the editor with nothing lost.