At a recent writing convention, I saw a panel entitled “Not Another F***ing Elf” in which four authors discussed the tropes of fantasy writing.  There was an interesting moment in the discussion when it was suggested that many twentieth century fantasy writers copied the basic elements of JRR Tolkien’s Middle Earth without fully understanding them.  The point made was that JRR Tolkien had created a living, viable world with history and language and culture that he understood intimately. It was argued then, as it has been before, that Tolkien only wrote The Lord of the Rings and his other books as a way of exploring, even proof-testing his world.
A great story will take us on a tour of a clearly realised world. The writer shows us around and doesn’t have to give us huge chunks of exposition to demonstrate the quality of their creation. That world may be a fantasy realm, a naval submarine, 1970s San Francisco or a one-bedroom flat. A great writer will enable the reader to feel that they know that world as completely as the author themselves.
JRR Tolkien’s world was vast, taking in whole continents, dozens of languages and thousands of years of history. Thankfully for most of us, our worlds do not need to be so large. In fact, there is a lot to be said for writing a novel in a world with restrictive geographical (and even temporal) boundaries. Apart from the weight of responsibility it removes from the writer, there is also the fact that humans, to one degree or another, like compact worlds.
Compact is clever. Compact is endearing and intriguing. Dolls houses, haiku, ships in bottles, Twitter and bonsai trees are all things that, as well as their other features, are somehow attractive to us because they attempt to contain the world in a limited space or form. We want to hold the world in our hands. In fact, one could argue that’s also one of the attractions of books over other media.
A collaborative novel may be easier to write and more enjoyable to read by setting it within a small world with very specific boundaries. An excellent example of this is Draculas by Blake Crouch, Joe Konrath, Jeff Strand and F Paul Wilson, which makes the conscious and canny decision to place their vampire epidemic novel entirely within the four walls of an isolated US hospital. Like a corset, this imposed limitation moulded and contained the novel. It simultaneously created a sense of claustrophobia for the reader, trapped in the hospital alongside the beleaguered protagonists.
When thinking of building small worlds, I am often put in mind of studio-based sitcoms.  Whether it’s Friends or Porridge, Fawlty Towers or Cheers, studio sitcoms make use of a very limited number of sets. The driving force behind this is, of course, budget – three regular sets is cheaper to film in than seven – but the limitation is actually a spur for great storytelling. Such stories are driven by characters and the interactions of characters within a limited number of locations. We’re wowed, not by the scenery, but by the stories.
Some sitcoms have taken the concept further. Victoria Wood’s dinnerladies is set entirely within the kitchens of a factory canteen. Roger & Val Have Just Got In not only takes place within the confines of a single house but also only ever features the two central characters and always details the first half hour after they arrive home in the evening. Both sitcoms are intelligent and tightly written and part of their success lies in these self-imposed limitations.
Whatever world you create as an author, it is essential that you know it well. If it’s a novel, you are probably going to be living there for several months at least. If there are forests, what kinds of trees grow there? If there are streets, what shops or businesses line those streets? If there are houses, flats and apartments, how many rooms are there and how are they laid out?
I realised quite some time ago that when I have a dream that takes place inside a house, that house is always one of three or four houses that I remember from my childhood. The residents of those houses and the decor and the feel of the house will change depending on the dream but the layouts remain fixed. I frequently use them as mental shorthand when using houses in my fiction writing.  
In writing our collaborative novel, Clovenhoof, Heide and I discovered that my mental shorthand had creating a spatial impossibility, a continuity error. Two of the central characters have flats on the same floor with front doors facing one another and yet, in my initial imagining, it was possible to enter either flat, turn left and be looking out the front of the building. This was a minor problem but one that needed fixing. A few scribbled building plans later and we were sorted.
Continuity can be a big concern in fiction and impossible or elastic geography can play a part in this. There are many movies where geography and people’s interactions with it do not stand up to close scrutiny. A notable example is in the otherwise excellent film adaptation of Tolkien’s The Lord of the Rings: The Two Towers in which the elves turn up to help Aragorn and friends at the battle of Helm’s Deep, having taken no time at all to cover a distance that apparently took the story’s heroes weeks or months. The reason for this is, of course, narrative convenience but it really should be avoided wherever possible.
If your novel is set in this world or a world with similarities to this own, one way to avoid errors and maintain a single shared world with your collaborator is to use maps and reference images. A simple map will prevent the hero of your London-based novel running from Tower Bridge to Big Ben in under five minutes. A series of photographs of the high street where your novel is set will ensure the collaborators equally understand the feel of the locale. Even if your novel isn’t set in this town or on that stretch of rugged coastline, a reference image can help you understand what the fictional location would be like.
Image referencing can be extended to characters. Actors, celebrities, friends and even random strangers can be cast as characters from your story. Even though my personal writing style doesn’t lean towards much in the way of physical character description, it is handy to know what a character looks like or indeed does not look like.
And what if your novel’s setting has no parallels in this world? Well, then that may be the time to break out the pad and pencils. Draw. Sketch maps. Design alien trees and fantastic beasts. You don’t need to be a gifted artist. Your work only needs to be of sufficient quality to convey your ideas to your collaborator.
And you can’t complain that you don’t want the embarrassment of sharing your amateur doodles with another person. Collaboration is an intimate business anyway. You aren’t merely sharing words or pictures. Your collaborator is a travel companion and fellow explorer. To collaborate on a novel is to blaze a trail through a world of your mutual devising, paving the way for the reader-tourists who will hopefully follow in your wake. Sort of.