I believe it was just the forest biome that looked dried out because it was surrounded with normal forest. The forest had like orange/brownish grass and the trees were spruce iirc (there was no snow in the biome). I know 100% it wasn't regrowth or crash landing because my friends and I played those 2 first a lot, and then this one that I can't remember the name of.
The one detail that sets it apart the most (that I can remember as I only played it for about 2 hours total and then it used all my pc's memory) is that you had to use mob heads to upgrade through the mining levels with Tinker Tools (The whole modpack was focused around advancing through the mining levels). I believe mobs were also pretty difficult to kill as well. The server was really resource intensive and required like 5-6gb ram to run, so it would've had to have a lot of mods. I played it back when there was only the FTB launcher, not curse. Also, it was in the "3rd Party Modpacks" list, however, it's gone now. It also had Hardcore Questing as mentioned in the OP.
I also remember it being very hard to survive, my friend and I died a lot and had tons of death markers and gravestones. All the vanilla MC tools were disabled and were only there just to be used in crafting recipes. For example, the swords did almost no damage, and the pickaxes took years to mine something, and didn't give you any block after mining it.
Also, on a side note, thank you guys for all the responses. I thought people were just going to look at the thread and close it. But I really hope someone knows the name or has played it before.
EDIT
It may have been the New World modpack, going to install it and check it out now. I looked up a video but the guy was using vanilla tools, but I'm still going to make 100% sure.
-Just checked it out, it wasn't new world. damn.