Here's a suggestion for continuing this game:
Oseo Bones
After Martha had been fucked by the dog, she couldn't quite forget the encounter. So she pays another visit to the basement and again got fucked. Of course, she keeps on saying that she shouldn't come again, but again she comes. And cums. On the next basement visit she doesn't wear panties, being wet and anticipating. She again encounters the dog, and while having an orgasm, the MC comes and sees it. Later, he fucks Martha and he has become wild. On the following day, she again goes back to the basement, and right after cumming with the dog, the MC reveals himself and fucks Martha, who again had an orgasm. So we just retain the dog fucking Martha in the basement in the game.