The Mainline Mario Games are the most important category of Mario games, where the story is mostly about how Mario travels to save Princess Peach of the Mushroom Kingdom.
The only mainline Mario games that are not focused saving the Princess are Super Mario Bros 2 and Super Mario 3D World. Super Mario Bros 2 is just Mario's dream and in Super Mario 3D World, Mario, Luigi, Peach and Toad are trying to save the Sprixie Princesses of the Sprixie Kingdom.
Mainline Mario Games are split into 2D and 3D games. The 2D games are shown as if Mario is a drawing on a paper and the 3D games are like the Zelda games or Fortnite, where the camera can be all around Mario and he can move in at least 8 directions.
The mainline 2D games are: Super Mario Bros (1985, for the NES), Super Mario Bros: The Lost Levels (1986, for the Famicom), Super Mario Bros 2 (1988, for the NES), Super Mario Bros 3 (1988, for the NES), Super Mario Land (1989, for the GameBoy), Super Mario World (1991, for the SNES), Super Mario Land 2 (1992, for the GameBoy), New Super Mario Bros (2006, for the DS), New Super Mario Bros Wii (2009, for the Wii), New Super Mario Bros 2 (2012, for the 3DS), New Super Mario Bros U (2012, for the Wii U), New Super Luigi U (2013, for the Wii U) and New Super Mario Bros U Deluxe (2019, for the Switch).
The mainline 3D games are: Super Mario 64 (1996, for the N64), Super Mario Sunshine (2002, for the GameCube), Super Mario Galaxy (2007, for the Wii), Super Mario Galaxy 2 (2010, for the Wii), Super Mario 3D Land (2011, for the 3DS), Super Mario 3D World (2013, for the Wii U), Super Mario Odyssey (2017, for the Switch) and Super Mario 3D World + Bowser's Fury (2021, for the Switch).
Other Mario Franchises include the Mario Kart series, Luigi's Mansion series, Mario and Luigi and Paper Mario RPGs and a few others
As of August, 2021, the top 10 Best Selling Mainline Mario Games are: Super Mario Bros (1985, for the NES, 40.24 million copies sold), New Super Mario Bros (2006, for the DS, 30.8 million copies sold), New Super Mario Bros Wii (2009, for the Wii, 30.32 million copies sold), Super Mario Odyssey (2017, for the Switch, 21.4 million copies sold), Super Mario World (1991, for the SNES, 20.61 million copies sold), Super Mario Land (1989, for the GameBoy, 18.14 million copies sold), Super Mario Bros 3 (1988, for the NES, 17.28 million copies sold), New Super Mario Bros 2 (2012, for the 3DS, 13.37 million copies sold), Super Mario Galaxy (2007, for the Wii, 12.8 million copies sold) and Super Mario 3D Land (2011, for the 3DS, 12.77 million copies sold)
