Preferred kinks: Rape, Slave, BDSM, Prostitution, Maledom, Corruption.
I prefer Female Protagonist because when you're the guy, the female NPCs always FEEL like NPCs, but if I control the character, I can imagine her with a personalty, etc. Honestly, it's also more interesting what's going on in the Sub's head. Games with good writing seem to recognize this. Take a look at
News Desk, you play as the Male/Dom, but all the sex scenes are written from your rival/sub's perspective. And they're way better for it.
All that being said if a game was done with NPC's that react and change based on your actions, I can see male protagonist working. The best game with NPC interactions I've seen so far is
Unholy Arts. You're an equal competitor for a role, and you can use domination and stuff to influence/change the other girls. The thing that makes this so great is that there's a bunch of sliding stats that change based on what you do, and more importantly EVERYTHING YOU CAN DO TO THEM, THEY CAN DO TO YOU! It's fantastic, and the only game I've played where the NPC's felt alive enough to make me want to Dom them. They have actual personalities. You can't play as a male in that one, but it represents a system that would do it well.
I prefer Corruption where she is gradually trained to enjoy it against her will/given kinks based on what is done to her. It's rare to come by but great when it shows up.
No Haven seems to have the structure to make this happen, but the execution hasn't occurred yet. Specifically the
Loaded Dice Mod seems to be working on a Player Slavery system. The PC is the leader of a Sex Slavery mercenary band, but can lose respect/have submissive tendencies, etc. If she (You can play as either gender, but I'm writing based on my kinks/playthroughs) loses enough respect, and has a dominant/unscrupulous second in command, he can start raping her at night and growing her submission. This is the best part of that game currently, but it doesn't go anywhere, and eventually the option to keep playing as the sub disappears as when she is truly overthrown the 2nd in command becomes the player character.
What I don't like however is how most Japanese games do it. A few horny dudes just shove themselves in and suddenly she loves it. It feels like the writers have never met a woman in real life *and* never bothered to read what women have written about sex/kinks. It's so much better if there's a true RIVAL of some sort, from either the Dom OR the Sub's perspective.
Another of my favorite games to date is
Whore Life, a mod to Girl's Life, but better than all the other content, as it has depth and progress. This one just hits my personal kinks extremely well with the forced prostitution. Honestly there isn't a single game out there that actually hits BEING a slave well, as the nature of slavery is a lack of choice. Whore Life finds an excelent middle road, where you HAVE to whore yourself for a certain amount of money each week, but outside that your choices are unchanged.