People and monsters who want to kill a character might be the most exciting part of an episode, but they're often the least of a player's worries. Exposure might not be a very heroic way to die, but a week living rough can make a big difference in that big climactic final battle, and a week wandering in the desert, or even a day without water becomes quickly life threatening, dire situation. Add to that getting lost in foreign lands without the right provisions, not knowing what's eatable, where's safe to shelter, which animals are dangerous and you quickly realize that the world can be as big and dangerous an antagonist as any monster if handled right - and not an unsatisfying one. The supplement The Land deals in more detail with navigating, orienteering, tracking, hunting and other rules associated with travelling in the wilderness, but a quick overview of the most common effects of the environment
Environment and Perception
The most obvious and immediate effect of a character's environment is how much they can be said to perceive. While is is common sense to know that high ground gives further views, and caves can carry even whispers, some conditions require a more formal, statistical approach to their descriptions.
Light and Darkness
Light and Darkness are relevant to vision, but vision is the primary sense of most advised player races, and so they can have a major impact on the game, from an extreme excess of light or its absence making vision useless, to low light conditions giving certain creatures advantages over others. However this is also very relevant to characters trying to employ stealth, and remain hidden in the shadows where they remain more invisible.
Sound and Silence
Equally important for stealth is having a solid statistical structure for sound, how far it travels, how its intensity is reduced by distance and direction, and how it interacts with obstacles.
Climate and Weather
What most characters are likely to encounter regarding the environment however are the predations of the elements, these will both effect senses - something as as simple as rain reduces visibility, how far sound carries and even how effective scent is for tracking, not to mention wiping out tracks in soil and so on, while something like the baking heat of the desert or the terrible cold of he far north will kill quicker and more surely than even the most dangerous beast dwelling there.
Temperature
Extreme temperatures are very much capable of killing, or severely weakening a character who is not used to them, or prepared for them.
temperature
intensity
penalties
Wind
High winds can alter the way sound and scent work dramatically, and especially high winds such as hurricane or tornado can pick up and throw characters and objects with ease, making them especially dangerous. In the desert high winds can cause sand storms, and in the snow blinding sleet.
force
magnitude
sensory
projectile
to wound
Dust/Dirt*
Sand*
Debris (small)
Debris (large)
Debris (very large)
*these projectiles also obscure vision as mist (see below).
Rain and Snow
Rain and snow, when falling, can obscure hearing, sight, smell and a number of other sensory-based information, as well as making tracking someone passing before difficult, but since much easier. However they also make things very slippery, making jumping, running and other such actions suddenly much more difficult, obscure vision, hearing and even smell, and get characters and their gear wet.
heaviness
traction
sensory
saturation
Mist and Fog
Mist and fog obscure vision, sometimes dull hearing, and really have little other effect, but they do it so completely that they are remarkable.
density
sensory
Storms
Storms do bring with them high winds and heavy rains, but the danger of flood, lightening strike and deafening thunder, that as much effect senses and present danger as other conditions, but also imparts the unreasoning fear of the divine in mortal beings like little else can. The rage of a storm comes with a terror, not for your safety, but of something infinitely greater than you, that shakes all the denizens of Allornus.
Fire
Fire is a great danger too, though forest fires are relatively rare in most of Allornus's climes volcanic activity, and superheated steam, magma and boiling mud are encountered now and then, as well as the faerie fires of the Starwood. However fire also provides light and heat, and often gets out of control in civilized ares, and fire makes an excellent weapon.
Foreign Environments
A landsman is at home in the fresh air, and when he is in the water or underground he is at a natural disadvantage when compared to a native of that region.
Movement
Moving through a foreign environment, water being the prime example, becomes difficult for a creature not native to that environment.
Actions
Actions, because most of them require movement of some kind, are also effected. Imagine how hard it is to swing a sword or fire an arrow when submerged in the sea, or how hostile a salt water environment would be to trying to read a book, or brew a potion! Most actions that become impossible are, of course, common sense, but again in the example of water the resistance of the general environment compared to air is extreme, and it becomes very hard to exert more than a fraction of your strength when suspended in water.
Breathing
Most land based creatures need to breathe air, and so lots of environments make suffocation a very real danger. The perennial example of water is clear, but also smoke or the natural gas deposits often found in caves will prevent a normal character from being able to breathe, and become serious quite quickly.
Food and Eating
A major part of survival being a part of the immersive experience of the Darkrealm game is characters need to eat, ideally daily, and either need to carry provisions with them, or be able to hunt for or forage for food when on the road.
Starvation
Characters who don't eat for long periods will become weaker and be at risk of death (though it is recommended that a Director rescue characters from such an ignominious fate when they have had enough time to worry), and characters don't last very long at all without water. This means that, while a game focused on eating and drinking is not very interesting, players must devote some of their character's time and attention to ensuring there is a healthy supply of food and drink available to them to survive, and if they are wandering through a desert and start to run out of water, or climbing mountains with low provisions, then a decision must be made to devote time to finding a source of sustenance or risking pressing forward and growing weak and hungry.