Cartridges instead of one game
Earlier home devices had their games built in. The Atari 2600 used cartridges, so one console could play hundreds of games. It had only 128 bytes of RAM, so programmers drew the picture literally line by line as the electron beam swept across the screen.
The first third-party studios
In 1979 four programmers left Atari and founded Activision, the first independent console game developer. Until then, game authors were not even credited.
The 1983 crash
The market was flooded with poor games, the rushed E.T. becoming the symbol. Sales in North America collapsed and the industry only recovered with the arrival of Nintendo.