Kevin Bunch (Ubersaurus from the days of the Digital Press forums) has created an exhaustively researched, excellent resource for classic video game release dates. [LINK]
These dates are North America-specific except where noted and are as accurate as I’ve been able to get them; refinements will undoubtedly happen as I come across new information.
It covers the Atari 2600, 5200, 7800, Intellivision, Channel F, RCA Studio II, Odyssey2, Bally Professional Arcade, APF MP-1000 (!!), Intellivision, Colecovision, Vectrex, and Emerson Arcadia 2001. It narrows down to the month what games came out when, and it’s annotated with the sources of those dates. Fascinating stuff.