Metaverses – Kinds of Connected Worlds


Note this is an excerpt from my masters dissertation An Inquiry into Designing Metaverses (2021), this is a study into designing and creating multiplayer virtual worlds and connecting those worlds into a wider virtual universe known as a metaverse. hosts a number of these excerpts broken into sections of particular interests. You can find all sections here or feel free to contact me if you would like a copy of the entire original document.


Worlds within the Metaverse

How do worlds within a metaverse interconnect? Are they physically co-related or is the metaverse a sequence of disassociated worlds? There are several approaches and combinations possible.


Mono World

This is mentioned briefly to acknowledge its possibility. A mono-world metaverse has a single unbroken world. It is similar to our experience of reality. All players and content exist within this single world, which has consistent physics and interaction rules. The mono-world metaverse is indistinguishable from a very large virtual world.

Sections of the mono world may function like puddle worlds, where an area or district may have distinct owners and physics. The structure of a mono-world metaverse makes modular design difficult, although such a metaverse is the closest to what is described in Snow Crash.

In practice this approach is unlikely to be successful as it does not scale well, and all player interaction is heavily dependent on the developer. That dependency forces up costs for the developer and also limits a player’s sense of ownership of the space. This limitation also hurts the developer as they are forced to regulate and moderate all content because they are responsible for it.


Puddle Worlds

My definition of a puddle world is based on C.S. Lewis’s book The Magician’s Nephew (Lewis, 1955). This describes a world where many disconnected worlds can be accessed by jumping into puddles or portals. These worlds appear to share many similarities, and beings and objects can travel between them; however, they are quite separate. The space that connects these worlds is depicted in figure 10; in the case of Lewis’s book there is only one connecting world, however in a metaverse there may be many.

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Figure 1 shows the illustration section from the cover of The Magician's Nephew. It features the world that connects all worlds, depicted as puddles in a forest. The characters are being pulled out of one of these worlds. © 1970 Macmillan Publishing Company


This is the most common form of a linked virtual world. It can be equated to the idea of levels in traditional video games. Metaplace, a virtual world’s platform, implemented this approach as an early metaverse design (Koster, 2013) and, today, Roblox and others use it.

Each puddle may have somewhat different physics. One might be dedicated to racing and contain a racetrack with cars. Another puddle may be more socially focused and offer many mini-games or other social entertainment.

Puddles, in these cases, are connected by a number of potentially shared properties. They are typically accessed through the same client so movement between them has low friction. The player tends to keep the same avatar in each puddle although the abilities of that avatar may change. Other services, like friend lists or chat, may be consistent across all puddles. In a metaverse that has an economy, money or items may be transferred or used in different puddles.

In player-generated worlds, the player is often only able to modify and create inside puddles they own or where they have received special permission to work. Players visiting puddles which they do not own may have limited interactions. This creates a separation between the creator and the viewer of a puddle.

In some situations, puddles may be non-persistent or single player, while still being a part of the metaverse structure. In this case, when a player enters the puddle they will be in their own personal copy of that puddle and will not perceive the actions of other players.


Leaf Worlds

Leaf worlds are puddle worlds with the capacity to inherit properties from a root or upper-puddle world. This could be considered a treelike-metaverse structure where the core of the metaverse branches out into puddle worlds, and those puddle worlds branch out into smaller worlds.

An example of this would be a world dedicated to racing. A player may wish to make a leaf world that would inherit all the cars and racing physics from a root world, but provide its own racetrack. Players visiting the leaf world might share their racing stats with the root world while racing in the leaf world.

In order to maintain compatibility with their root world, leaf worlds must conform to a set of rules defined by the root world. Such conformity, and the additional content provided by the root world, are the main differences between leaf worlds and puddle worlds.

A leaf world can be considered a first step towards a glass world. The base world and the leaf world both act as glass layers.


Glass Worlds

Glass worlds are a single world made up of many transparent ‘layers’ or sets of content. The glass world only exists within the player’s client. The player displays the layers they wish to see, one on top of another, similar to the way in which augmented reality displays virtual content over the real world. The virtual world, in this case, exists only in the player’s client and is made up of people and objects pulled out of many worlds, all existing simultaneously.

An analogy of this can be seen in animation slides. In traditional animation you have many parts of a character drawn on transparent film, and each glass sheet of film can be stacked and moved to form a whole character. I am unaware of any active or past implementations of this type of world connecting in a virtual world; however, it is quite developed in the field of augmented reality.

The player uses a client which can subscribe to or download layers of content provided by developers. These layers can be moved around and organised by the player into a cohesive world. The player may then send these layers back to the metaverse for others to access and modify. In this sense, the player’s client can be regarded as a puddle world itself. The player can freely modify the world within their client in any way they wish and have full ownership of their experience.

Maintaining compatibility between the layers is the primary challenge to this approach. For example, a developer may wish to provide a glass world with a building for the player. The player may want to fit that building into a city supplied by another developer. To accomplish this, it would be helpful if both developers used a standard size and coordinate system within their layers. This agreed system might suggest that players are a particular size, so buildings should be proportional to that size. Developers might also wish to agree to standardised city layouts, fitting their buildings into an agreed grid or street plan.

As with puddle worlds, we would see some shared properties. All clients may access the same chat systems or economies, regardless of the layers they are accessing. Alternatively, properties could be bound to layers. A glass world may contain its own economy and the player could access multiple economies within their client by accessing multiple layers. Likewise, multiple chat systems, multiplayer systems, and world physics may co-exist, depending on the player’s glass world selection.


Koster, R. (2013). The Ready Player One MMO was Metaplace. Retrieved from

Lewis, C. S. (1955). The Magician’s Nephew.