The 'Platform' game object on EditorScene is a Level Editor tool that runs in Editor Mode. I will try to write a short guide.
- First you need to load one of the current levels from the 'Scenes' selectbox.
- You can see and select GameObject prefabs under the Prefabs folder in the selectbox named Object Group.
- You can add the selected object to the scene with the green Add button. Red delete button will destroy the last object added from the scene.
- The 1st and 2nd Checkpoint count textbox lists the checkpoint numbers of the selected and loaded scene and serves as an input to update it.
Also JSON file can be found under the Assets / StreamingAssets folder. The template scene is the only scene in the build and the prepared levels are played through this scene.