Labyrinths is a open universe based around the post game of Chasms, as well as some foundation built via Persona ID.

The setting primarily takes part in Mazehart, a town once named for the maze-like paths throughout out the city, and now for the chasms that have opened up throughout the city. This was due to the work of Lety, a slime who gained enough sentience to question life above the ground, and thus, cause the chasms to bring herself -- and the slimes living underground -- to the surface. Now, those equipped with the watches, which provide otherwise normal humans with Personae, go into the chasms not only to protect humanity from the creatures that have surfaced, but perhaps, with time, learn to live with them. But, little did most know, this wasn't the first case of supernatural activity....

In reality, several years prior, it was the Amnesia Incidents -- events where countless people suddenly lost their memories -- that the first cases of supernatural activity became recognized by humans. And these humans, after gaining persona through means other than the watches, learned that demons were responsible for these incidents, decided to band together to stop them. The events that unfolded not only resulted in stopping the demons, but coming into contact with the Seraphim and, eventually, changing the very laws of the world. This instance came to be known as the Merge -- and is suspected as to why the slimes in Mazehart's underground suddenly gained the power to wield magic and accrue knowledge.

While everyone has their own plotlines, the bulk of the adventures that I (Rubin)'s characters go through can be found at this link.

Additionally, note that given the setting, the events of DRcade also prelude Labyrinths. Because of this, characters from the Labyrinths setting are also known to play the more recent DRcade ONLINE, which was launched sometime after Chasms was resolved.