This feature was added in the 0.3.34 release! If you are on an earlier version, please update Kartridge before proceeding!
The option to tag your game will appear during the publishing flow, on the Game Information page.
From the publishing Menu, select for the game you would like to add tags to. On the edit game page, go to the Game Information section.
The category choice will automatically add your game to the chosen section of the filter page. Tags will help make your game easier to find in search, and your game will appear to anyone who searches for a game with that tag!