Nintendo last week announced that its next mobile game will be "Mario Kart Tour," but with a launch date aimed at any time before the company's fiscal year ending March 2019, not much information is known about the game. Today, DeNA CEO Isao Moriyasu was reported as saying that Mario Kart Tour will be free-to-start (via TouchArcade and The Wall Street Journal).
The "free-to-start" terminology is somewhat vague, but when compared to Nintendo's previous use of the phrase it could suggest where Mario Kart Tour is headed. For example, Nintendo currently describes Animal Crossing: Pocket Camp as free-to-start on the game's website, while Super Mario Run's website explains that "you can download and enjoy a portion of Super Mario Run for free."
While far from a definitive answer, this suggests Nintendo might lean towards its recent trend and make Mario Kart Tour a game that's free to play, with in-app purchases that help with certain tasks. Out of Nintendo's four mobile games so far, three have followed this model (Miitomo, Fire Emblem Heroes, Animal Crossing: Pocket Camp), while only Super Mario Run has used the pay-once price tier.