The conceit of Messages from the Universe Graveyard is that it takes place in a defunct MMO, still accessible but no longer being maintained. The MMO's actual gameplay is no longer available, but you can wander through deserted spaces that are varying levels of glitchy and read messages left by other players, as well as leaving messages yourself.
On the meta level of the game, there is a little bit of exploration-based gameplay; scattered throughout the game are teleporter-like "apparatuses" that will take you to a new location if you type in a number, and both the messages and the environment descriptions sometimes contain references to new numbers to try. There are also story threads to follow within the messages as various characters discuss the lore of the fictional MMO and their own lives, which take some strange and surprising turns.
The locations are atmospheric, with descriptions that are usually short but evocative accompanied by photos with fuzzy filters. Some of these locations seemed familiar from other works of fiction that involve people being trapped in a supernatural place—I spotted a bathhouse and a “red lounge”. I did enjoy exploring them just for the sake of seeing what new weird places I might encounter, but mostly I was thinking about the crumbs of story being doled out to me. In particular, I spent a lot of time wondering which of them came from the original author and which were additions from players. The first few comments in any given location are usually clearly in-universe, and then there usually follows a chunk of comments from usernames I recognize, mostly not trying to uphold the kayfabe of being in a transdimensional MMO. But then, in amid the commenters I know are real people, there are comments from people like “the Pizza Guy,” a fast-food employee who seems to be (Spoiler - click to show)dead and haunting the game. Is that a later addition by the author or a player adding their own story to the setting?
But this is probably missing the point a bit. While Messages from the Universe Graveyard doesn’t offer actual MMO gameplay, it is, in its own way, inviting players to roleplay. As is customary for roleplay, a setting has been provided, and players have the opportunity to imagine their own character for that setting and work them into the existing fabric of the narrative.
Or you can be like me and leave inane comments referencing ancient Tumblr memes. Whatever floats your multiversal boat.