Rankings
GameRankings collects and links to (but does not host) reviews from other websites and magazines and averages specific ones. While hundreds of reviews may get listed, only the ones that GameRankings deems notable are used for the average. Scores are culled from numerous American and European sources. The site uses a percentage grade for all reviews in order to be able to calculate an average, however, because not all sites use the same scoring system (some rate out of 5 or 10, while others use a letter grade), GameRankings changes all other types of scores into percentages using a relatively straightforward conversion process.
When a game has a certain number of reviews, it is given a ranking compared to all other games in the database and a ranking compared to games on its console.
Read more about this topic: Game Rankings