Ask HN: Game development resourses?

I am a developer interested in starting game development for mobile devices as a hobby. I've been looking around and since I already know C# I belive Unity will be a good engine to start learning. I'm more interested in 2D games.

I'm looking for any recommendations, online resources/tutorials or good books that you have used or are using that can help me.

Thanks so much, anecdotes are welcome too!