That's an interesting experiment. I myself am trying to learn how to draw adequately, as I've noticed it's way easier to prompt even if you use low quality drawings as a basis.
Hard to say which is 'easier'. With a branching VN, you need to plot out all the different branches quite a bit, while with a sandbox you can get away with railroading the player to only a few endings.
What I mean is, if the player has a ton of freedom, they'll consider it acceptable to only...