Whether the jungles of South East Asia, the taiga of Siberia, or the ancient mixed woodlands of Europe, forests fascinate me. I like being in them and I like thinking about them: to be in a forest is to be completely surrounded in a gaia-like ecosystem, made all the more interesting because it obscures your vision and plays tricks with sound. This means that exploring a forest is a bit like exploring an overland dungeon - you never know what is around the next corner.
There is also some sort of primitive fear - the fear of a Savannah-dwelling early human/primate - of those dark, closed-off, cool spaces. To stand in an open space looking at a wood is like standing at the threshold of another, different world. A world where you don't belong. A wild place.
Woods are not like other spaces. To begin with, they are cubic. Their trees surround you, loom over you, press in from all sides. Woods choke off views and leave you muddled and without bearings. They make you feel small and confused and vulnerable, like a small child lost in a crowd of strange legs. Stand in a desert or prairie and you know you are in a big space. Stand in the woods and you only sense it. They are vast, featureless nowheres. And they are alive.
But there are difficulties running games in forests realistically, by which I mean, without just being yet another bunch of adventure locales except featuring treants, dryads and wood elves rather than derro and drow and whatnot. Taking advantage of, and emphasising, the uniqueness of the forest as an environment. I think there are chiefly three sets of problems.
1) First, as Bryson also puts it, when describing the experience of actually walking through a forest for day after day:
There is no point in hurrying because you are not actually going anywhere. However far or long you plod, you are always in the same place: in the woods. It’s where you were yesterday, where you will be tomorrow. The woods is one boundless singularity. Every bend in the path presents a prospect indistinguishable from every other, every glimpse into the trees the same tangled mass. For all you know, your route could describe a very large, pointless circle. In a way, it would hardly matter.
At times, you become almost certain that you slabbed this hillside three days ago, crossed this stream yesterday, clambered over this fallen tree at least twice today already. But most of the time you don’t think. No point. Instead, you exist in a kind of mobile Zen mode, your brain like a balloon tethered with string, accompanying but not actually part of the body below. Walking for hours and miles becomes as automatic, as unremarkable, as breathing. At the end of the day you don’t think, “Hey, I did sixteen miles today,” any more than you think, “Hey, I took eight-thousand breaths today.” It’s just what you do.
Existing in a mobile Zen mode is nice, but not really what an RPG session is all about. In other words, exploring a forest is fun and interesting, but in reality also full of nothing-much-at-all in terms of excitement, danger, and adventure.
You can add excitement, danger and adventure with random encounters, of course, or hex locations, or even pre-planned encounters, for that matter, but at some stage it seems to me that if you're doing that too much you're not really being faithful to the nature of being in a forest as opposed to other sorts of environment. Emptiness and featurelessness is part of what journeying through a forest is.
2) When you are walking through a forest, you get surprised by things all the time. It's not an environment for humans (unless perhaps you are born into a tribe in the Amazon, and even Amazonian tribespeople manipulate their "forest" environment a lot). Your senses don't function well there: your main strength is sight, which is rendered defunct by the lack of visibility, and in comparison to just about any animal you could name, you have pathetically rudimentary senses of smell and hearing. The long and short of it is: whatever is round the corner knows you are there before you know about its existence. You are forever flushing grouse, being scared out of your skin by sudden bird alarm calls, and trying to identify the sources of mysterious movements in the undergrowth. You could be hunted and stalked with embarrassing ease by any serious predator.
This would make for good natural world as survival horror gaming (there is death lurking everywhere and it will get you) but not, I think, a long-term campaign.
3) Forests are in a sense featureless, but if at any given moment you stop while walking through one, you will be confronted by a radically different geography than you would have five minutes earlier. There are inclines, crevasses, streams, clearings, fallen trees, boulders, pools, a whole array of different features swallowed up by the trees and undergrowth and suddenly revealed to you as you pass by. More than in any other environment, the surroundings really matter - there is stuff everywhere.
So a realistic encounter in a forest has to take account of that. Want to fire an arrow? Deal with the fact that it's more difficult for your target not to be in cover. Want to creep up on an enemy? Deal with twigs and dried leaves everywhere. It's not so much that there's plenty of scenery to interact with, it's that you are overwhelmed by scenery; you have scenery up to the eyeballs, more scenery than you know what to do with.
This, among other things, makes forest adventuring - doing justice to what makes a forest a forest - one of the true last great frontiers of gaming.