MobyGames is a video game database that has been online since 1999. Its goal is to give a detailed description of every video game ever made including packaging, screenshots, release information, developer credits, technical requirements, reviews, and more. I've found it to be the most detailed and complete video game database online.
I came across MobyGames in the mid-2000s while I was searching for more information of some of my favorite video games. The site has since become my go-to for pretty much all information about the specifics of video games. I have helped update several entries on the site.