koobas.hobune.stream
Add Color Overlay to 2D Unlit Images
I am creating a 2.5D Overworld and looking to add a color overlay to my Alpha Channel 2D environment artwork, based on the time of day. As an example, here is a Tree environment Prop: 
...And now here it is with a red/orange overlay for "Dusk" lighting (done in Photoshop for this question):
Instead of doing this manually within photoshop and having to drag and drop all new 2D image files into my overworld (save out multiple time variations of the same file i.e. "Tree_Day.PSD", "Tree_Dusk.psd"... etc.), there must be a way to simply apply a script or shader that sets all 2D GameObjects to "Dusk", adding the red-orange color overlay. That said, I can't seem to find anything online for unlit alpha channel images.
Any help, relevant links, or advice on where to start with this is appreciated. Thank you!
I found this link, and "Final Shader" shows the effect I am looking for. But because my 2D objects are "unlit" I am not seeing the shader applied.
Link example on a soldier: 
Link: https://docs.unity3d.com/Manual/SL-SurfaceShaderExamples.html
