Am I the only one who thinks this game is wildly overrated? The relationship with the mother is barely developed at all - right from the start, she adopts the goblin and starts loving him more than her own son, so there's no real sense that your mother is being 'taken away' from you. The dialogue is sparse, and what little there is feels pretty cliché and silly. The queen doesn't even try to resist the goblin.
And then at the end, when she so easily gives up on her love for her husband and son (during the sex scene) - it just completely kills any remaining immersion. Overall, the plot feels like something out of a basic porno, with no attempt at eroticism, let alone something resembling a visual novel. I'm honestly really surprised to see so many positive reviews.
That said, the sex scenes themselves are fairly well-drawn and described - I'd say that’s the main strength of the game. So yeah, not a bad porn novel, but definitely not NTR.