Monster Girl Dreams is a text based BFRPG made in Ren'Py. (The BF stands for Battle Fuck.)
In Monster Girl Dreams you play as a male adventurer, freshly graduated from the adventuring school, Adventum!
Now you must venture across the home continent of the monster girls, Lucidia, in an attempt to get rich, or get fucked into submission trying. Also defeat the Demon Queen. Maybe.

At the start of the game you create your character and define their combat stats and weaknesses in a point buy system, and must choose at least one fetish for the monster girls to exploit with their temptations.
Gameplay functions similar to many standard turn based rpg games, but you utilize numerous sex techniques to defeat your female opponents, all while not trying to give into the enticing pleasures they offer.

Monster girls will have an array of status effects and temptations to throw at you, as well as the ability to put you into multiple sexual stances. They will probably also use their numbers to pin you down and fuck you silly!

But you'll be able to get the edge of your opposition by leveling up and choosing perks to help define your play style as well as equipping various items to boost your sexual powers even further, or to help make up for a weakness.
Or you could just say screw that, running forward without any planning, and get ravished into unconsciousness by the lewd monster girls.

You can also spend time getting immersed in the games whimsical setting and (usually) upbeat tone as you get to know some of the monster girls.