How to create/import new scene

First of all – you can simple create new 2D scene using standard Unity tools and objects.
There are only 2 strict requirements: all “active objects” should have common parent and each of them must have attached Collider.

If you want to import new scene - the easiest way is to create image(.PSD as instance) with layers (each piece should be in separate layer) end then export it to bunch of images + data-file.
It's recommended to have postfixes(like “_shadow”) in layers names, those allows to specify is layer overlay, shadow, ActiveObject or HintObject.

I've prepared a small GIMP script for you (please check _GIMP _ExtractAllLayers.chm in Scripts/Utility folder) - to export such image from free "The Gimp" ( editor really fast and easy.

Thescriptwill createfolderwitheachlayerexportedas.pnganddatafiletoparse.DragthisfoldertoyourProject window in Unity.

The Gimp can open PSD files, so if needed - you can save your image to .PSD from Photoshop and then open in GIMP to use exporting script.

Kit has built-in script (_Scripts/_Editor/_SceneImporter.js) to create atlas and generate scene using this data. You can run it from Unity menu (Main Menu -> Assets -> Import HOG Scene...) and select text data file: 

In the utility window you also can specify:
- Max size of generated atlas
- Postfix for special objects (hint, shadow, overlay)
- Quantity and names of layers/images, that should be excluded from atlas and created with separated material

Info for manual exporting (just in case) :

- each layer/piece should be saved to separated .png file
- info about all layers must be saved to text file with structure:

Layer_3.png - layer/file name
723 - X position of layer in the image
790 - Y position of layer in the image
75 - X size of layer (width)
91 - Y size of layer (height)
-------- - separator-string before information about next layer