one of the problems with IF erotica is that it's generally written in a vacuum. minimal descriptions of anything but sexual acts, shallow implementation in general, and heaping helpings of read-the-author's-mind. even when the writing per se is good (e.g., Deanna) there's an inherent feeling of artificiality; much like bad porn, it just kind of starts at the sex and ends after it.
in order for an erotica game to work for me, at least, i have to understand what the characters are like, how they feel about each other, and what this means for them. to put it another way, i need the backstory.
(i acknowledge that there are some people who do prefer their porn to be storyless and characterless. to this, i reply that they are free to howl "get on with it" at my kind of erotica, just like i'm free to be bored and mildly revolted by theirs.)
"And the Robot Horse You Rode In On" is unapologetically a work of erotica; the author has even acknowledged that it began with a mental image of (spoilered for sexual terminology) (Spoiler - click to show)predicament bondage and expanded from there.
but for a work so short, it does an excellent job of characterbuilding and worldbuilding. you can understand your character. you can understand the other character. you can understand how this arose and where it might go.
well-written, engaging, and very, very hot.