Because it is, somehow, an actually very well made game. One of those things where I first just learned about the anime and just thought that sounds dumb, but man the game is actually fun. Also the recent spinoff anime series (cinderella gray) was actually just a very good sports anime.

Umamusume is a gotcha game

Small nitpick, but it’s actually “gatcha” or “gasha” because it comes from the Japanese word “gatchapon/gashapon”. The word is derived from two different Japanese onomatopoeias:
Gasha - The sound of a toy capsule dispenser handle being cranked/turned.
Pon - The sound of a toy capsule landing in the output slot of the machine.

Basically, you know those little coin-operated toy capsule dispensers that you can find in arcades? The ones that have little toys, stickers, candy, etc. inside? They usually look something like this:

Yeah, these things are wildly popular in Japan. They’re colloquially referred to as “gatchapon”. There are massive stores full of these gatchapon machines. Brands will do promos for new anime, TV shows, band album releases, etc… Collectors spend a lot of money to get the rare collectibles from these machines, because not all the toys are the same rarity.

And a gatchapon game is the same basic concept, but in a digital format. You get pulls/draws/{whatever the game calls them} via some method (usually purchasing them, because that is usually how the game makes money), and then those pulls are used to get new things. Sometimes characters, sometimes equipment, sometimes new outfits, etc… It’s literally gambling, because the best stuff is virtually always gated behind some hilariously small jackpot odds.

Again, small nitpick. I just think it’s interesting (and horrifying, because it’s literally slot machine style “keep rolling cuz the next one may be a jackpot” style gambling) how much the mobile game market has come to rely on gatcha mechanics in recent years. There is a lot of (well deserved) condemnation of loot boxes in kids games, but somehow gatcha games have managed to skirt around it.

Thanks for this invaluable insight into the epidemiology of horse girls.

I live in the south now, I only give it away when I’m wearing an Avs sweater or a Donkey jersey.

But you are SPOT on from when I lived there.

Ok, I am not familiar with either 'elder emo girls' nor 'tail girls'.

Elder emo girls does not make sense to me at all, because emo girls are essentially the exact opposite of horse girls.

Horse girls learn how to do things, many things, practical things, and be good at them.

Emo girls are angsty, and make bad poetry or art, then usually either phase out of that, or transition into rave/scene girls, develop serious drug problems, and then basically work in retail or customer service the rest of their lives, with few exceptions... maybe a few become tattoo artists or become actually halfway decent at some other kind of art.

Perhaps you are thinking of elder goth girls?

Not the same thing as emo, not even close.

Tail girls?

I... do you mean a furry, some kind of anthro/humanoid type person?

No, I've never known a single horse girl that became or also is/was a furry or puppy girl or anything like that, again they tend to be extremely practical and utilitarian, they tend to be fairly domineering, task/goal oriented.

They just also have eccentric hobbies/interests, in my estimation due to the relative social isolation of either literally living away from a lot of other people, on a farm or ranch, or at least spending so much time at a farm or ranch that they're not as enmeshed in 'normal' society.

They do not need to fantasize an alternate identity as an animal, because so much of their lives involve very real and often traumatic experiences with animals, so they understand them in a much more grounded and realistic way.

Like, a horse girl walking past a furry at a convention is likely to make a passive aggressive 'joke' about having some extra dewormer, if the furry needs it.

They're cocky, self-confident, haughty... better than you, lol.

so you're trans horse phobic 🤨️

Now that is equality.