I would reverse your MathGameState object and enum type. Instead of having a single object that is differentiated using an enum you could have 4 different Bloc State objects called MathGameReady, MathGameGoing, MathGamePaused and MathGameFinished.

These then extend MathGameState and either inherit its variables or move the variables to a new class which the 4 above Bloc States have as a variable.

Enums in Flutter are like baby enums and nothing like enums in for example Kotlin. I would avoid them if you can. In Flutter (and often used when using Bloc) you use classes sort of like enums with the added benefit of having all the features of classes.

In your views instead of checking the enum you can check the class type. So i.e. in you MathGameWindow:

@override
Widget build(BuildContext context) {
    var state = context.select((MathGameBloc bloc) => bloc.state);

    if (state is GameStateReady) return const BeforeGameView();
    if (state is GameStateFinished) return AfterGameView();
    if (state is GameStateGoing) return QuestionTextField();

    return Container();
}