Unsurprisingly, Nintendo needs a little more time to polish its mobile-friendly version of Mario Kart. Beyond the name and target platform, we know precisely zilch about Mario Kart Tour, which was originally scheduled to come out by March 2019. But we haven't seen a single screenshot or Nintendo Direct-style video explaining what the game is like or how it works. So it wasn't a huge shock when the company announced today that the game is now scheduled for summer 2019. Why the delay? "In order to improve [the] quality of the application and expand the content offerings after launch," Nintendo explained in its Q3 earnings report.
In the meantime, you'll just have to polish your skills on the Switch with Mario Kart 8 Deluxe. Or dip into Nintendo's other mobile offerings, such as Fire Emblem Heroes, Animal Crossing: Pocket Camp, Super Mario Run or the action-RPG Dragalia Lost (provided it's available in your region, that is.)