Matthias, Jonax - thanks.

I wonder, as it is MMORTS, what happens if I log off and someone attacks. I will be an easy target in this case, right?
Yes, at any moment any other player will be able to attack you. For protection, you can build defensive structures such as towers and walls. The wall has a lot of HP, absorbs and reflects most of the damage, and can be upgraded as long as there are enough resources.

The source code is not available, right?
Sorry, in order to prevent desync, the code will not be available. It's a multiplayer game, after all.