Several years ago, I wrote a game about sentient animals in a caste system, vaguely inspired by the early myths and caste system of Hinduism.
It is called "Rajah Spiny Rat". Highly experimental and probably not very playable, but filled with great ideas that have filtered through into my more recent work.
It has basically sat available in a few locations with neither promotion nor revision...but for some reason, every couple of weeks someone somewhere downloads a copy. It would be nice to think that there are other people around the world breathing life into this text, or maybe using it to inspire their own games.