The relevance of the subject “game-related phenomena” is associated with the increasing importance of new cultural phenomena in modern culture (cosplay, let’s play, video blogging, fan art, fan fiction), which nonetheless rarely become the subject of cultural and philosophical reflection. We suggest exploring “game-related phenomena” from the standpoint of modern mythmaking. The concept of “game-related phenomena” is proposed to denote a number of sociocultural phenomena related to video games, but which are not their immediate part (cosplay, let’s play, fan fiction, fan art, e-sports, etc.). The object of this research are cosplay and let’s play. The purpose of the article is to analyze these cultural practices as forms of modern mythmaking manifestation. It should be noted that there are very few works devoted to the study of “game-related phenomena” through the perspective of modern mythological consciousness. Cosplay is a specific practice of creating and wearing a costume that allows fans reconstruct the image of a fictional character in popular culture. In this work we highlighted the main approaches to the study of cosplay: cosplay as (1) a way of constructing an identity; (2) a form of escapism; (3) a mass culture phenomenon; (4) a subculture. We have also presented a critical reflection on a number of existing approaches. Let’s play is a video created by users in the process of walking through a particular video game, combining gameplay and commenting it. Main results of the research. Firstly, we have proven the imaginative nature of cosplay. A cosplayer is an active participant in the creative reality transformation and myth construction. A cosplayer appropriates cultural texts and images, creatively processes them, creating one’s own myth on their basis, which attracts the audience. Secondly, we have revealed mythological identification of a reality image and reality itself, as well as the work of the mystical participation. Mythological images created by a cosplayer are thought of as quite real, one can quite feasibly interact with them. The image depicted by a cosplayer is at the same time the original, which introduces him/her and the audience to something larger, for example, to the fictional world, to the fandom, etc. Mythological images and meanings constructed in the framework of cosplay have a sacred meaning. Thirdly, we have shown the interconnections of cosplay with archaic mysteries, carnival performances, medieval theatrical performances that transmitted the sacred into the real world. The cosplay phenomenon itself, in our opinion, is rooted in archaic ritualized practices within which the mythological narrative attained its being. However, unlike archaic mysteries, cosplay is more eclectic and kaleidoscopic in terms of constructing images with different semantic and symbolic content. Fourthly, we can interpret the let’s play as online storytelling. Like a myth narrator, a let’s player narrates on one’s own behalf, constructing one’s own story not based on the original source. Let’s play from the standpoint of studying forms of modern mythmaking appears before us as a space of imagination, creativity, and playing with the original source. A let’s player makes secondary marking of video game elements, building on new meanings and meanings based on them, which allows you give new meanings to original narratives. So, we have come to the conclusion that such “game-related phenomena” such as cosplay and let’s play can be considered as forms of modern mythmaking.