Hello, I want to create a 2d strategy game, something like pc version of Risk board game with some bonus elements from eu4, hoi4 etc, so basically turn based strategy game. It'll be both single- and multiplayer. Problem is the engine - everyone says that Unity is the way to go, but it's a 3d engine and it seems to be an overkill for me, as I don't need all that 3d stuff - everything will be showed on 2d map and on few popups/maps/windows and units will be represented as numbers with icon. So, maybe there is some gamedev beginner friendly sdk/engine/whatever to use? I have some C# and C++ experience, but I'd prefer to use C# since I will be trying to get a job/internship in this language in the near future.

And are there any good resources/tutorials on how to make AI and how to implement multiplayer?

There are a few options.

Unity is an option, and they now have 2D tools available to help make the type of 2D game you're talking about.

But if you're truly a beginner then I'd recommend GameMaker by YoYo Games. GameMaker is built to make it as easy as possible to learn how to make games, and a number of successful 2D titles have been built with it.

You can check out the conversation I had with them at GDC this year. It was a great learning experience for myself, because as someone with more experience I didn't realize the possibilities with GameMaker:

Their website is http://www.yoyogames.com/.