Nintendo announced last night that it will be bringing the classic color-matching puzzle game Dr. Mario to Android and iOS devices in 60 countries as Dr. Mario World early this summer.

Nintendo said the game will be "free to download with optional in-app purchases" but didn't go into detail on how exactly the monetization system would work. Many mobile puzzle games (such as the Candy Crush series) use timer-based "energy" systems to limit the amount you can play without paying in a certain period. Nintendo has used similar cooldown timers in games like Animal Crossing: Pocket Camp and Fire Emblem Heroes, though other Nintendo-developed mobile titles have used other monetization methods.

Dr. Mario World is being co-developed by Line, a Japanese mobile developer mainly known for the messaging app of the same name. Nintendo had previously partnered with Line for sticker packs in that app but had relied on a partnership with DeNA for games like Super Mario Run and Miitomo. Nintendo also owns a five percent share of mobile developer Cygames, which released action-RPG Dragalia Lost with Nintendo last year.

Mario Kart Tour, which was initially announced over a year ago , is also currently planned for a launch on mobile phones in mid-2019, according to Nintendo. And the Wall Street Journal reported back in 2017 that Nintendo was working on a mobile entry in The Legend of Zelda franchise, though no details of such a game have been officially announced.

Originally released on the NES in 1990, Dr. Mario has seen occasional re-releases on various Nintendo platforms over the ensuing decades. The latest of these, Dr. Mario: Miracle Cure, hit the 3DS in 2015.