Ren'Py Futa Mystery

Futa Mystery is set in the fantasy world of Scardya, where a war between northern women and southern populations broke out after the women learned to manipulate Essence, the natural energy that transforms them into Futas, a much more powerful and sexually unstable form.

They created the Futocracy, an expansionist empire that has conquered many regions over the decades. The protagonist was born in one of those invaded regions and would have ended up a sex slave if not for a futa general who took him in. That protection ended at 18, when he was forced to make a pact with the Goddess of Freedom and became an adventurer.

The 2DCG art, animated scenes, big-ass and big-tits design carry the look. Female domination, futa/trans, MILF, fantasy, monster, and creampie content all factor in. The focus is futa-on-male and male-on-futa, with a few sissies along the way (avoidable). If you want a serious futa-empire fantasy with real worldbuilding, Futa Mystery delivers.