"Nintendo hard" is an informal term used to describe extreme difficulty in video games. It often refers to games with trial-and-error gameplay and limited or nonexistent saving of progress. The enduring term originated with Nintendo Entertainment System (NES) games from the mid-1980s to early 1990s, such as Ghosts 'n Goblins (1986), Contra (1988), Ninja Gaiden (1988), and Battletoads (1991).