Mike Meier - Lewd Sibling Duo v7.1 (Win/Mac)

LSD features two main protagonists, brother - a prominent young biologist, and his older sister - a college professor. On a quest to rid the population of a terrible infertility plague that threatens the very existence of humanity, they discover that their solution has some interesting side effects on women.
Changelog

Update 6.0:

- over 70 new rendered images

- 2 new scenes

Update 6.1:

- fixed many grammatical errors and typos, thanks to envixer