Future Love Space Machine is a science fiction themed sex game. You can download it for free and and if you want more characters and positions you can buy it in the addons store.
The game just went live this year and it doesn't have alot of options yet but they are working on great addons like character creation, a nice palace room and more. The game has nice graphics and great potential.
I personaly like the space theme and it makes this game unique.
Check it out! http://futurelovespacemachine.com/