The Puzzlebox is an arbitrarily large, arbitrarily old, arbitrarily weird region of the Mess, an even larger, older, but rather less weird transhuman habitat. Most of the Mess is et up as a fairly mundane, unchallenging, comfortable existence for any sentient, offering freedom from death and want.
The Puzzlebox has the same conveniences overall; no one need die or go homeless or hungry, but unlike the rest of the Mess, it's divided into vastly different areas, each one seeming to have its own very forceful personality. Each of these six Warps, as they're called, has slightly different rules of reality from each other and the rest of the universe, that support their own particular ways of life. Given its oddness by the general standards of the surrounding habitat, most Mess denizens look at the Puzzlebox as down-rent property, generally to be avoided.
However, another thing that makes the Puzzlebox different is that it seems to have a will of its own, and a penchant for collecting. Strange immigrants are common there, from far-flung areas of the Mess and from other realities entirely. Many of them aren't even sure how they got there. In general, there's nothing keeping them from leaving again, but those that the Puzzlebox chooses seem to tend to find a place there, preferring it to wherever they came from.
The Puzzlebox is divided into six warps, three pairs, each named after a flavor of quark. Each warp seems to be as big as it needs to be, but borders between them can be found as well, the particular reality of one warp bleeding into another in the far reaches. There are rumors of other places too, specific junctions between two or even three warps, but details on these are sketchy at best.