Moving to the Freeuse World!

A parallel Earth turns up next door, identical in every way except that sex is casual, constant, and apparently the default social contract. Scientists poke a hole between worlds and, naturally, someone has to go live there.

The setup drops a male protagonist into this other Earth to navigate its wide-open rules, presumably from the vantage of a school setting that treats "freeuse" as normal curriculum. From there it plays out as a sandbox: wander around, meet the women of this world, and see who's willing given that everyone already is.

Expect the usual sandbox rhythm of exploring locations and building up to the women in his orbit, cosplay, milfs, group scenarios, and voyeuristic peeking included, since the whole point of this world is that nobody's hiding anything.