4Gamer (translated on NeoGAF). There's the racing phase, obviously, during which players control their horse with the stylus. The other phase involves playing solitaire – the card game – to train and improve the bond with your horse. The two phases alternate throughout the race until a horse (hopefully yours) crosses the finish line. Players will be able to trade horses with one another using QR codes.
Soriti Horse is slated to hit the Japanese 3DS eShop on July 31 for ¥500 ($5), and it will be self-published by Game Freak. The horse racing / solitaire genre isn't exactly thriving in the west, but it's worth mentioning that Game Freak's last eShop game, Harmoknight, did receive a western release.