written long ago about the flow of news in a large game world. Person to person news spreads slowly, imperfectly, unevenly. You can outrun it. Most current large game worlds don't have organically flowing news at all. When non-player characters pass on news relevant to the progress of a plot, it's not because news has spread to them by the natural process of character talking to character, it's because the developer has intervened and scripted it. And, of course, in games I want to write, I still want the developer to be able to intervene and script such things - where it's essential to the plot that that character should have that news.
However, there's more to the spread of information than news. Sometimes the player character must communicate with allies - either other players or non-player character allies - who are distant. Most current generation role playing games would introduce some magical device - a scrying mirror or whatever - which allows instant communication. But I want to radically limit the use of magic in my games, simply because an incoherent magical physics leads to an incoherent world, while any coherent magical physics which is more than trivial tends to ruin plots. The god should be lowered out of the machine only rarely, and never in plot-destroying ways.
So, messaging. How would real bronze-age or iron age heroes have communicated with distant allies? Well, one way is to send a messenger. That means hiring a non-player-character messenger that the plot gives you reason to trust. You've got to find that messenger. The round trip time is just the round trip time for a journey over the distance, which is to say thirty kilometres per day if the messenger is on foot, about 120 kilometres a day if on horseback, about 160 if by sea with a fair wind. Obviously the cost of the hire has to be enough to pay the messenger a premium over what he could earn from his normal occupation over that period, and enough in addition to cover the expenses of the trip. So it's quite slow and quite expensive. And if you want a message back you've got to agree a rendezvous point with the messenger (or a poste restante, possibly an inn), and you've got to actually get there. The messenger may also be unreliable, either in failing to deliver the message or being suborned by an opposing faction.
The alternative is pigeons. Pigeons will return to their home loft. Pigeons are quite light, and can be carried for a time in quite a small cage. So a hero might carry two pigeons in his pack, or four on his horse, or up to perhaps a dozen on a packhorse, in addition to normal equipment, without adding excessive weight or bulk. However, the pigeons could do only one thing: take a message to their home loft.
To get a message back - even just confirmation that the message had arrived successfully - the character sending the message would have to be somewhere which had a pigeon loft, and, additionally, the loft to which the pigeon had been sent would have to have a pigeon in stock whose home loft was where the player was. Presumably allied centres which had pigeon lofts would exchange pigeons regularly for precisely this reason, and perhaps you would have a class of non-player-character whose job was just to trundle round between allied pigeon lofts with a horse and cart (or possibly boat), exchanging pigeons.
Of course, the pigeons would not always arrive. They could be lost for a number of reasons, including but not limited to hawking by opposing factions. The probability of a pigeon going missing should probably be a function of the square root of the distance (or some other power root, but two is approximately right). The probability of a message falling into the hands of an opposing faction (assuming there is an opposing faction at this point in the plot, which if a player is sending a long distance message there almost certainly is), is probably about half the probability of a pigeon going missing in the first place.
The possibility of pigeons getting lost and messengers being suborned, of course, puts a premium on in-game cryptography, making it a valuable skill for players to learn.
But I think slow, unreliable long distance messaging would add considerably to a number of possible plots, and it would be easy both to explain in narrative terms and to implement.