Dr. Mario World Has Just Released!
The title is technically "free-to-start," so it's not clear how far you can play before before hitting a paywall. Microtransactions do exist within the game. Players can open what are basically loot boxes to gain the aid of different doctors, like Dr. Peach, or Dr. Bowser. The game has a single-player campaign and an online competitive mode. You can download the game for free on iOS and Android right now.