Your favorite adventures and livestreams owe more to Sandy Petersen's Call of Cthulhu than Gary Gygax' Dungeons & Dragons. Here's why.
Dungeons and Dragons might have invented roleplaying games, and created an entire industry, but modern roleplaying has more in common with Call of Cthulhu than with the first editions of D&D.
If you've ever played a modern RPG adventure like Icewind Dale: Rime of the Frostmaiden, or had one of those sprawling campaigns with beautiful visual handouts, or been all over the world on globetrotting (but interconnected) adventures, you're feeling the influence of Sandy Petersen and the Call of Cthulhu. It's hard to overstate just how influential this adventure has been. It's a lot like Casablanca, because many of the things that we take for granted now, Call of Cthulhu did first.
One of the most basic shifts that Cthulhu brought about was a shift in the role-playing landscape. Until 1981, RPGs were broad, but even early editions of more narrative games like Glorantha were more interested in how you fought than in investigation and interaction. Call of Cthulhu changed that, framing the game instead on the classic tropes of Lovecraft's stories--exploring the unknown and learning truths you wish you hadn't.
After all, you can't have a fear of the unknown without having something there to not know about in the first place.....