We are glad you enjoyed the game! Linked below will be the video that we used to implement the black lines in our game. The video might be a little out dated and you may need to do some tweaking. We would be happy to make a detailed post about how exactly we got it to work, if this is something a lot of people are curious about :)
Thanks. I see, so it's a clever trick with backfaces. They need to be bigger than actual faces to be visible though, I wonder how the shader does that, especially since it works in web. Not sure I would understand the answer without a huge headache though, implementation details can be overwhelming.