Linux Tycoon:
http://lunduke.com/linux-tycoon/

Infamous kraut pedo game:
http://unteralterbach.net/index.en.html

FreeCiv - explicit:
http://freeciv.wikia.com/wiki/Main_Page

Scorced3d - Pretty nice (looks like Worms in 3D):
http://scorched3d.co.uk/

Visual novel with tactical elements. You are a captain of a space ship and your crew is full of qts:
http://sunrider-vn.com/sunriderpage/
https://github.com/vaendryl/Sunrider

Obligatory tux racer: