Scarlet Slayer
Action RPG game where you play as a sexy vampire hunter fighting sexy vampires, and also having sex. All this hot sexiness has courted a bit of controversy, because won't someone please think of the CHILDREN who play this smut?
The game's defenders point out that the sexiness is equal-opportunity: there are sexy men and women in spades (both with a variety of body types represented), the player has multiple gender options, and the game's presentation of sexuality is intended to be empowering rather than exploitative. Not surprisingly, this doesn't totally convince everyone.
Despite all the controversy, the game actually has really good combat, with a wide array of cool weapons and powers.
Developed by HeavyTungsten Games, the makers of the Gabriela's Gate franchise. They have promised a sequel, Scarlet Slayer II: Bloodlust, which promises to be everything great about the original, but moreso.
Not surprisingly, the source of a ton of fanart in certain corners of the OmniNet.