I love films with the styles of "Outland", "2001 - A Space Odyssey", "2010 - The Year We Make Contact", "Red Planet" and "Mission to Mars", so I thought about a setting which would work for the XStoryPlayer.
I thought about a crew on an interplanetary mission, an expedition to Jupiter (and maybe Saturn) and its moons. You as the player are either the artificial intelligence of the ship (like HAL 9000), or you are the ship engineer, and as this or that, there is the possibility for mini games like managing and repairing ship systems (pulling components out and putting things together, wiring some things, a little programming; ideas could be found in puzzle flash games), course corrections or starting probes for moon exploration.
Since the ship doesn't have FTL-drives of any sort (Faster Than Light), your ship (let's call her Discovery for the moment

) travels the traditional way as it is shown in 2001 for example (Gravity Assist), the science crew is in stasis, cold sleep or whatever you want to call it. I am not sure how many people are in your crew, but at the moment I would suggest a crew of three: You as the engineer and two female scientists. You are awake because you have to keep the ship running, the women are sleeping.
One of the sleeping capsules fails and a scientist wakes up, and while you fix it, you have the chance to get to know her better aside from your mission through spending free time, talking, playing games, eating together, doing and helping with some of her work (the mini games I suggested before), and by spending so much time together, she develops a crush on you. I suggest she's a nerd girl, not overwhelmingly beautiful, but not ugly either, a nice, curvy build.
Because you are the engineer and responsible for maintenance, there might be an incident where you accidentally spy on your crew mate, namely activating the cam of the computer in her quarter and catching her masturbating with a (huge) toy. She cries out your name on orgasm. From now on, it can be possible that you see her masturbating in other positions at the same time each day, or when she says that she "is going to her quarters to study/sleep".
Finally the day has come and you tell her that you fixed her sleeping capsule, but surprisingly, instead of scaring her off with sex-crazed behaviour you have won her affection and she doesn't want to go to sleep, she wants to stay awake with you, so both of you get it on.
EDIT: I can remember that there was a somewhat related idea somewhere around, something with the female starship crew getting lost in holographic illusions and the player (as some engineer or so) blending into it. I wanted to add this idea to it, but I couldn't find it. If someone finds it, he is welcome to put a link to it in here.