Greetings Paragan,
Thanks for mentioning Knight of Xentar because it was just a few minutes ago I started thinking back to what my first erotic game was I ever played, which was the first Leisure Suit Larry game back in '87 (probably got it in '88 or even later, considering things didn't go as fast as now regarding release dates) and the first one that blew my mind back in the day was Knights of Xendar that came out in '94, but I still own the original '96 cd-rom edition (speaking about English releases). I didn't play any erotic game for ages after that, which brings me to now...
Games of today can't be compared to Knights of Xendar for a few reasons: first of all however awesome I considered it at the time, it is as tame as can be these days! I was happy as can be be funny German soft-erotic movies back in those days when seeing a boob was the shit! Could you say the same now though?
Times have changed, morals have changed and most of all... erotic games changed from erotic innuendo to... well... if you can imagine it, it's somewhere around and most is (compared to Knights of Xendar) hardcore as fuck!
If you have changed with the times as erotic games have and I personally have and still want something kinda like Knights of Xentar... I can only give you one great tip which is going to the main page while logged in. got to Latest games and updates, to the right select Prefix Status: Completed and since RPGM and Wolf RPG are closest to KoX atm, select them under the Prefix Engine.
From there you can go where you wish to go using the tags...
Go crazy, go wild and enjoy the journey as you did so long ago in Knights of Xentar!
Enjoy!