Nintendo Game & Watch for Sale

 Series:

• Silver (1980)
• Gold (1981)
• Wide Screen (1981–1982)
• Multi Screen (1982–1989)
• New Wide Screen (1982–1991)
• Tabletop (1983)
• Panorama (1983–1984)
• Super Color (1984)
• Micro Vs System (1984)
• Crystal Screen (1986)
• Nintendo Mini Classics (1998)
• Color Screen (2020-2021)

Most of the titles have a "GAME A" and a "GAME B" button. Game B is generally a faster, more difficult version of Game A, although exceptions do exist:

• In Squish, Game B is radically different from Game A—the player must touch aliens to eliminate them as opposed to avoiding moving walls.
• In Flagman, Game B is a mode where the player has to press the right button within a certain amount of time, not memorize patterns.
• In Judge, Boxing, Donkey Kong 3, and Donkey Kong Hockey, Game B is a two-player version of Game A.
• In Climber, Balloon Fight,  and Super Mario Bros., there is no Game B button.

In most cases, both Game A and Game B would increase in speed and/or difficulty as the player progressed, with Game B starting at the level that Game A would reach at 200 points.