I was not sure what to write for the prompt Forest, but then I remembered Symbaroum.
Symbaroum is a great RPG. It is one of those where the art sucks you in and makes you want to play.
The forest connection is that the forest in Symbaroum, Forest of Davokar, is a massive part of the evocative setting. The forest is the place where people are scared to go, that is where the adventure is to be had and it is where the evil lies.
The creatures that inhabit the setting make use of the forest and are part of the forest.
Elves are ‘not nice’. Spring and summer elves are the young and are the least deadly, but when you get to the autumn and winter elves, this is there forest and you will probably not come out alive.
In all my years of roleplaying, Davokar is the single forest that really stands out. That may not sound like high praise, but I come from a Rolemaster/Middle Earth Role Playing and spent many IRL years in and around Mirkwood. I am not saying that Symbaroum beats all the lore and nostalgia of Middle Earth, wouldn’t that be contentious, but the way in which the forest of Davokar is made a big a threat to the heroes as any creature or monster is great setting design.
So my answer is the forest of Davokar, Symbaroum.