OK, I got your point. Probably I am pampered by stable and well designed APIs of components, and rich professional documentations in the past. The game development industry seems to be a way more challenging. Thats the lesson I have learned the past view weeks. Why I have digged into UE4 is, because it offers a C++ API for free, compared to Unity. I think the unreal engine itself is one of the best grafik engines around. And I even loved it to play the unreal games in the late '90.