Steam faces a stampede: horse girl game Umamusume: Pretty Derby is "actual cinema," and a massive hit on PC with 5,000 overwhelmingly positive reviews after a week

If you're unfamiliar with horses, imagine a big, skittish dog with short hair and really long legs. Now imagine horse girls. They're like horses, but they're girls – girls with little horse ears and tails. Finally, picture horse girl racing, which is like horse racing but with horse girls. Congratulations, you are now equipped with all the knowledge you need to start playing Umamusume: Pretty Derby, a massive Japanese mobile game that recently launched on Steam in English with the kind of momentum and reception that any game would kill for.

At the time of writing, Umamusume: Pretty Derby has 5,017 user reviews on Steam, with an overwhelmingly positive grade score of 95%. It came out on June 24. Even for a free-to-play port of a years-old mobile titan, those are pretty impressive numbers

"Umamusume. They are born to run," the game's endearingly dramatic, almost romantic Steam page begins. "They inherit otherworldly names, and are inspirited by dreams most dramatic and wonderful. Now, they run ever forward. That, is their destiny. No one knows how the races that lie in their futures will end. Even so, they continue to run, aiming only toward the goal in front of them."

Here's the rub, building on the horse girl thing from earlier. Umamusume: Pretty Derby is basically a sports management sim gacha game with gambling stuffed into every possible corner. Collecting horse girls is an RNG gamble designed to encourage spending, and the races themselves are painstakingly modeled after actual gambling-laden horse racing, complete with live commentary, come-from-behind twists, and the real horses the girls are based on.

It's kind of ingenious, honestly. It was an instant hit in Japan, where horse racing is ha-yuge, and its global PC launch is already massive. You play as a trainer looking after horse girls and helping them win races. The horse girls also perform idol concerts; don't worry about it.

The game's wiki has a handy new player guide, which can basically be summed up as: collect and interact with Umamusume, watch some cute little animated snippets every now and then, boost their stats, keep them happy, and watch 'em run.

That being said, this is serious business, as many new Umamusume players were shocked to discover. Get this: gambling is fun, and rooting for your favorite horse (girl) can be emotionally intense, especially when you've become attached to them via story and character developments. Victory is sweet but defeat is bitter, and somebody has to lose. It's like a sports anime designed to squeeze money out of you – though in fairness, people do say Umamusume is 'free-to-play friendly,' which is of course damning with fine praise, but hey, it's still praise.

"I never praise gacha games but Umamusume is insane. Actual Cinema," one player reports in a viral clip, watching their girl surge to the front of the pack for a close win.

The top-rated user review on Steam offers a good demonstration of what this game can do to people. Behold the words of Gekko:

"I gave her the best shoes, the best meals, trained her under the clearest skies, and yet… she lost. She stumbled on the final corner, and I stumbled as a trainer, no, as a human being.

"How do I look her in the eyes after this? Those bright, hopeful eyes that once sparkled with dreams of victory… now clouded with tears. 'I'll win next time, Trainer!' she said, forcing a smile through her trembling lips — but I knew it was for my sake."

Their closing remarks offer a somber warning: "If you're reading this… cherish your horsegirl. Don't make the same mistakes I did. Because sometimes, it's not the race you lose — it’s her trust."

If that sounds like fun, the game couldn't be easier to try, and as ever gacha games give out tons of free stuff following major launches and milestones like this. If you're interested in the whole racing thing but understandably despise gacha systems, you can also give the Umamusume anime a watch. I'll tell you right now, for all the genre's obvious flaws and hazards, there ain't no animation like gacha-funded animation.

I walked an hour in the rain to play horse girl gacha game Umamusume: Pretty Derby at the actual Kentucky Derby.