It would probably be overkill to make a whole cat-themed TTRPG just to have mimics shaped like cardboard boxes.
Sir Whiskers, roll a WIL save to resist the urge to sit in the cardboard box mimic.

The obvious name for this game would be Katzeritter, but I worry that would launch a thousand turf wars with the Mausritter set.

Of course, we'd have the advantage because we're detachment class. But that just doesn't seem fair.