Hello I'm currently doing some research on programming languages(compile time reflection area, if you ask) and I found that on the game engine area the reflection feature becomes a must, an engine either uses a language which has reflection feature itself(for example uses C#), or implements it for non-reflection languages(for example both UE and CryEngine implement reflection mechanisms for C++).
I'm not a game developer, so I have no experiences on game developing and not familiar with engines, so can anyone tell me in what case the reflection becomes a must? And what's more, does reflection used only in development phase or also used in released production?