Publisher: Atari

Atari made the Atari 2600, which first went on sale in September 1977 as the Atari Video Computer System, and it also published many of the console’s games. Nine cartridges were available at launch, among them Street Racer, Surround and Video Olympics. Over the next years Atari’s programmers wrote original games and converted arcade hits, both Atari’s own, such as Missile Command, and licensed ones from companies like Taito, Namco and Williams. Sears sold many of the same games under its Tele-Games label, often with different names. The Atari name here also covers the later Atari Corporation, which kept releasing 2600 cartridges until 1990, among them Solaris, Radar Lock and Xenophobe.
This archive includes Atari’s released games as well as prototypes that never reached the shops. Some places to start:

Video Olympics (1977): 50 Pong-style games and variations for paddle controllers.
Video Chess (1979): a full chess opponent squeezed into a machine with 128 bytes of memory.
Warlords (1981): Carla Meninsky’s castle-smashing game for up to four players.
Missile Command (1981): Rob Fulop’s version of the arcade game about defending six cities.
Star Raiders (1982): first-person space combat with a galaxy map.
Solaris (1986): Doug Neubauer’s space combat and exploration game.

The full list is below, and every game on it runs in your browser.