Hentai Game 
An eroge set in space titled Creature Reaction Inside the Ship! 2 has naturally selected aliens to be its main form of female torment as two unlucky females are overwhelmed by the grotesque critters, who rape the girls in every way possible several times throughout the game.
The two main heroines work as space police and they end up receiving an SOS signal from an old freighter, but upon investigating it, they soon learn it is infested with sex-hungry aliens that take advantage of the girls at every chance they get.
Creature Reaction Inside the Ship! 2 and all its animated rape-heavy scenes are available now.
