Keep the free-roaming aspect of BT, that was supercool. Just add more positions, customizability for the chicks, and some "progress" (ball size was a nice way to make "progress" in BT and rewarded you with hotter chicks to bang). The ball sack thing made it slightly RPG. Awesome. I don't mind the fighting, but not too much please. BC was bad storywise. No sexual buildup. No free roam. No "reward" for kicking people's asses. BT was sooo much better at that.

Just having a free "world" to explore with hot chicks and trying to get them to fuck you is a major turn on. Work on that. I don't know, maybe introduce more pickup lines, work on your "MOJO". Use the ball size thing, I don't know. But free roaming a world full of hot (and fat) chicks is just the bomb.

You could also add some RPG to it. Maybe your fuckspeed, durability, quality of your pickup lines, your looks, your sexual creativity. All that stuff could then interact with the amount of positions you have, the amount of girls who dig you, how easy it is to pick up a girl. How long you last, whether som chicks will dig a threesome with you. At some point you could also get a "reputation": maybe some hot chicks heared that you fucked a lot of girls, and approach *YOU* for sex. Or the opposite way, and you have to convince them that they are "the real one". That would be super cool as well. I know the ball size is a sort of reputation thing though, you can keep that. But maybe sometimes a chick approaches you. Anyway, some more RPG style, more dialogue maybe? Seducing the girl with dialogue would also add to the sexual build up. Think of games like "Artificial Academy" by Illusion (a Japanese game). You could build up relationships with the girls there, and then fuck them. The relationship buildup was crude, but very interesting. You could ask them how their day was, etc. etc, and that would grow their affection for you. You could also say the wrong stuff and that would make it harder. You could add some sort of dialogue options to influence the pick up of girls and maybe improve your pick up RPG-stats.