I found a cool easteregg and I thought why not share it with you guys. I will give you a little hint where it is, so curious people can find it themselves, but I will uncover the actual easter egg below.

So the easter egg is located in the control room of the dam, you will have to press the button on the dashboard first, so the monitors turn on. On one of the monitors you can see something written in green font. I'll let you figure out what is actually written there for some extra tension ;-)
If you don't know how to read what's written there use this: a binary translator.

This is what's written on there, for the people that don't want to wait:
"help me! I'm stuck in the south tunnel B2."

I have actually not progressed any further, so I am not sure if this is going to spoil anything of the following story, but I think it is quiet a nice touch to the game :D