I like horses. I like horse racing games. I like games that let you selectively breed creatures to make them strong, faster. I have no ability to create mods at all. I would want the breeding to be fairly difficult, or at least, take quite a bit of time to get a dream stock going since you'd likely be able to sell your horses. Also, it'd give you an infinite amount of horses like Frost if he say.. suddenly launches into the air 60 miles and dies. Custom colored horses from combining breeds would be cool too.
And hey, maybe there'd be a way to implement horse racing? I think that'd be a fun past time.