Cheaprealms
The Cheaprealms are a plot device within Heirs of Rage. They are pocket dimensions where time moves notably faster than in the normal realm.
Overview
The Cheaprealms are mentioned in passing between the Heirs, as it appears that is where they were raised. Everett notes that he was in his Cheaprealm a little too long, to the point where he aged past his father.
There is only one named Cheaprealm, known as the Inescapable Realm. This is the cheaprealm Mari trapped Marc in after he split the Enragement Ring. It's nothing but shoddily-placed mountain tiles surrounding a small valley in the center. Inescapable Fate plays on (an improper) loop forever in this dimension, much to Marc's disgust.
Trivia
The Cheaprealms are a clear parody of the Deeprealms, a near-universally reviled concept used in Fire Emblem Fates that allowed the child units to fight alongside their parents.