Which 1986 Nintendo game was the first to use a battery-backed save feature in its cartridge?

The Legend of Zelda was the first Nintendo game to use a battery-backed save feature in its cartridge.

Nintendo released the game for the Family Computer Disk System in Japan in 1986 and for the Nintendo Entertainment System in 1987. The cartridge version used battery-backed random-access memory to preserve a player's progress after the console was switched off.

This feature was especially important because The Legend of Zelda offered a large, nonlinear world with many dungeons and items. Players could record progress instead of completing the entire adventure in one sitting.

Metroid is sometimes named in discussions of early console saves, but its original cartridge did not use a battery save system. The Legend of Zelda's save capability helped establish persistent progress as a standard role-playing and adventure-game feature.