Editing world parameters

To edit world parameters you must first be in the world edit mode (use the globe-icon button in the toolbar).

Changing gravity
The direction of gravity can be changed by rotating the gravity arrow as you would for other items. Hit 'R' to begin rotation, then use the mouse to rotate it. Cancel the rotation by hitting Escape, or click the left mouse button to confirm the change.

You can also edit the gravity vector values directly in the properties panel. The properties set here will be used for player views of this scene, and they will output in the JSON when exporting the scene.