How to setup dockerfile for steam client?

Question

ubuntu

I decided to play around with Docker - there were no problems with terminal images. Everything works as intended. But here with the X-application it does not work out in any way.
I tried about a dozen images from the Docker hub, tried to edit the settings - none of them could be launched. I came across an interesting Docker article: running graphical applications in containers - the player from the article started up fine for me. So the whole thing is in my crooked hands)
In general, I took the dockerfile from this article as a basis and started cutting it - 30-50 times the file rules, installed the image and killed it again, but I could not automatically start the Steam client. Either he doesn’t have enough libraries, then he doesn’t want to work from under root, then something else comes out ...
Here is the resulting dockerfile (gist)
The problem is in the last lines - removing the Steam libraries and starting the Steam itself. If you comment out these lines, and therefore manually delete these libs in the terminal mode and start Steam, then everything is OK - the client works. But still, I would like to achieve that it starts automatically with the launch of the container.
Base system: Ubuntu 16.04 x64