If you don´t care about graphic, maybe even like oldschool gaming i can tell you about 2 games that have great gameplay and very good sex scenes.
The Legend of Qeen Opala and The Legend of Queen Opala II Episode 1+2
Made by a woman all by herself! fantastic.
Meh… don't really agree with the "great Gameplay" for the Queen Opala Games... buy up to date armor and foes usually don't do any damage, which makes combat fairly boring. Also has that typical JRPG char development... where you can't do anything. XP only for active party members etc. Plus it is a bit on the grind heavy side... kill n mobs, to unlock Legendary Monster, kill Monster to unlock some art.(Even worse, if you don't know which monsters actually spawn Legendary Monsters^^) Requirements to forge certain equipment are also kinda insane at times...
So gameplay has it's ugly spots at least.
Don't get me wrong I do like Gabe's game (and hope we see the final part some day^^). Story at least does not suck, characters and dialog are kinda nice, some great humor here and there and a huuge amount of unlockable/collectible content, topped with a good amount of naughty stuff and sex (although too much Monster and Bestiality for my taste...) And of course there's Farah!!!
@topic in general
Well I prefer games with some actual gameplay I hardly consider the stuff a game, where you choose a scene, watch it and maybe decide how to finish. And I have no clue why people like these visual novels... hear some portraits talk for HOURS just to see some sex scenes every now and then... and hardly any interaction except a bit of path branching... nah not my cup of tea...
So in general I think the Queen Opala games are a nice template... a proper game with sex as a prominent element, that does not feel forced (at least not too much)
Not some sex scenes wrapped in a bit of pseudo "gameplay". Or a normal game with a tiny bit of "sex" thrown in for... dunno... maybe to claim "look we have sex". Who had guessed sex with Aphrodite could be such a letdown (God of War III)
I think the Witcher II is the only mainstream game that doesn't do a terrible job in this regard... that Triss scene in the Elven ruin is almost hot^^ (Oh and btw. I think TW2 gameplay and combat suck as well)