Hi! First, thanks for your interest in Penguin's Cape and sorry for my delayed response.
So... there are a few parts of the project I can not share with you for reasons beyond me. (for example the assets have copyright and all that stuff).
Therefore, I don't know if the source code would be of any help with you. That being said I can discuss the technics I used, and some of the resources I used.
I think these two videos are a good starting point:
For the stealth part be sure to email me if you're interested, or if you want to see particular things of the lighting of the game:
