A short (<1 hour) "slave training" game. Basically a hentai flash game.
Once you get through a prologue in which you need to "buy" the girl in an auction by doing some very specific steps, you start her daily training.
You get 5 "tools" to use on her (all are immediately available), each of which is more "difficult" to use than the previous one, meaning it drains her stamina faster. Using a tool can give her orgasms, increase the interest for the tool and increase the passion (sensitivity) for the tool. The goal of the game is to get her passion for each tool to 70.
The good
+ the sex mechanics are simple, but functional. You don't just read about sex, you actually have sex with this girl.
+ there is a sense of progression - you receive experience for orgasms, which increases her level and raises stats (allowing for more orgasms)
+ decent 2D animations help immersion
+ sound, including her moans, helps immersion
+ since half of games here are just linear clickfests, an extra point for this being an actual game
The bad
- no story, no meaningful choices
- two characters, zero personalities. The girl is just an object.
- a small amount of mostly engrish dialogue
- the UI is a bit clunky
- some questionable game design choices (the auction, stats lack explanation or balance, downtime when waiting for her stamina to recover...)
If you don't mind rape and a lack of story, it's worth a try for the gameplay.