The site lists tens of thousands of games, from the Atari 2600 onward, but plenty of titles still aren't in the database, especially on PC and newer hardware. If you have a review ready to go, you don't need to wait for us to add the game listing.
In the editor, when submitting your review, type the game's title in the games box. If it isn't found, you can add it from there, along with its system and details. If your account has permission, you can also submit new screenshots at that time.
Once you submit your contribution, it all goes into the staff queue. Staff check periodically for new content (and receive notifications on the site).
Keep in mind that we don't separately list Virtual Console games, or Nintendo Switch Online titles. That's why you don't already find them with separate listings on the site. Otherwise, most games are fair game (heh).
If you want to write about a game that we elect not to add to the database, or if you want to cover a game from an angle other than a conventional review, you are encouraged to post about it on your blog.