I had this game growing up and LOVED it. There are three different types of games you can play, but I always played the mustang one: you are a wild mustang and have to lead your herd to the safety of a valley while adding new horses along the way. Each individual horse gets its own card with breed facts and a picture. The artwork is actually pretty good. You learn about equine behavior and about different horse breeds as you are playing.
Herd Your Horses is probably most popular with horse-crazy girls from the ages of maybe 8 - 14 (that is a rough guess). The game works with anywhere from 1 to 4 players. There is even a solitaire- style game that you can play with just the cards. This was one of my favorite games to play when I was young, because I was (and still am) obsessed with horses. Kids that don't like animals may not care much for it though. I got this game when I was a child so other than at amazon.com, I'm not sure where to find this game anymore.