For many years
https://www.mobygames.com/ had it as something of an aim, still good stuff.
At the same time gamefaqs does well for a lot of things.
Today
https://www.giantbomb.com/ also does a lot of stuff here and some consider the forefront of such a thing.
"imdb but for games" (by the way imdb actually has a fairly decent amount on games) is not quite a thing. You might also have trouble getting database info from some of the sites mentioned before (such places seem rather protective of their data).
You have some "alternative" sources as well for some things.
http://www.advanscene.com/ ,
http://www.no-intro.org/ + all the other dat sites ,
http://abgx.net/ ,
https://abgx360.xecuter.com/verified.php and general scene searches will get you more info than you might imagine.
The trouble tends to come in the open devices. For the NES then you have a fairly fixed amount, plus a few tengen games. Same for most things from Sega, Microsoft and Sony. The open consoles, or the relatively open devices (IOS and android technically have gatekeepers, give or take what the Fortnite people are doing --
https://www.theregister.co.uk/2018/08/03/fortnite_security_fears/ , but practically... there is a reason we started to see the big review sites for andrios titles demand payment to bump you up the list). Start dealing with the PC, stuff like the C64, amiga, atari, amstrad, bbc micro... all of which have games fundamental to the history of the medium and that gets harder as you get things released, or indeed "released". Hacks, homebrew and mods... many of which represent fundamental shifts in those games (how many dominant titles either owe their success to mods, or started life as them?).
