cartridge-based games
8-bit microprocessors
introduction of battery-backed RAM for saving progress
improved graphics over previous generation
introduction of D-pad controllers
introduction of light gun accessories
introduction of more complex sound chips
introduction of multi-button controllers
introduction of peripherals like the Power Glove
introduction of save game functionality
introduction of scrolling backgrounds in games
introduction of third-party game development
rise of Japanese video game industry
revitalization of video game market after 1983 crash