Fictional “GameFan Magazine” from Retro Game Challenge. Not to be confused with the real-life GameFan Magazine, this is the magazine about the made-up retrogames in the compilation. Players can look through these magazines in-game to learn secret codes and tips about the fake games in the DS cartridge. In addition, the magazine offers previews of yet-to-be-unlocked games.
And, yes, game industry in-jokes. Being that this whole game is somewhat of a parody of gaming culture, such content hardly seems inappropriate.