Forest with druids and rangers in mind. I was designing it for a module and thought I'd share. It is one area, but saved as a module because of Module Properties scripts.
It requires the CEP hak, but works on basic NWN.
This area includes the following
1) No resting unless you are around a campfire.
2) No campfires without firewood. You can find it by itself, or chop it from dead logs, or cut down trees.
3) No lighting firewood without being a ranger, druid, or having a torch in your hand. The wind tends to blow out torches earlier than normal...
4) The campfires will eventually burn out, or you can put them out. Either way, they leave an ash mark.
5) Druids automatically start with an item called "Detect Creatures" which was inspired by a Ranger Tracks script I found in this vault. When used, the Druid will point to the nearest living creature, invisible or not, and be able to identify the basic type (undead, animal, outsider, etc) of all creatures within range (range based on the druid's level) and give a rough direction. Druids cannot detect other druids or rangers.
6) There is a premade trigger called Ranger Tracks. Anyone besides a druid or ranger who walks through this trigger, will leave tracks for 10 minutes. For the first 5 minutes, those tracks can be identified by rangers (by walking through the trigger). After that, rangers can detect them (by walking through the trigger), but can't ID what sort of creature made them.
7) The placeable trees, when attacked, fight back through vines and roots that attempt to entangle the attacker and transform them into a tree.
8) There is also a small creature called a twig ent roaming around stealthfully, protecting the trees as well.
Feel free to give suggestions, and I can tweak it...