Outline

Add an outline on all objects of the layer having the effect. This won't work well if shown on top of the background color of the scene. Be sure to use an object acting as a background or a floor.

Use Thickness to set the width of the outline and Color of the outline to change its color. The outline is drawn around the visible (non-transparent) pixels, so it follows the silhouette of sprites rather than their bounding box.

Reference

All effects are listed in the effects reference page.