HandleMakeMoveCommand.cs

public List<IEvent> Handle(MakeMoveCommand cmd)
{
    if (EState.Created == State)
    {
        return new List<IEvent>
        {
            new MoveDecidedEvent(cmd.GameId, cmd.PlayerEmail, cmd.Move)
        };
    }
    else if (EState.Waiting == State)
    {
        if (Player == cmd.PlayerEmail) throw new ArgumentException($"Player already in game: {cmd.PlayerEmail}");
        return new List<IEvent>
        {
            new MoveDecidedEvent(cmd.GameId, cmd.PlayerEmail, cmd.Move),
            MakeEndGameEvent(cmd.GameId, cmd.PlayerEmail, cmd.Move)
        };
    }
    else
    {
        throw new InvalidOperationException($"Invalid game state: {State}");
    }
}