Quoted from yancy:
Stranger Things, kind of old news. It's already run the full mainstream hype cycle. Three of four seasons are complete. The kids are going to be shaving by the time season four airs. I love the show, but it's run its course.
Rick & Morty is just on the cusp of transitioning from cult show to mainstream hit. As evidenced by this thread, a large portion of (non-young) people had literally never heard of it. It already seems huge to those in-the-know, and will only get bigger over the next 70 episodes. Only a third of the total episodes have aired. And there's already ten times as much material as you can cram into one game. Perfect timing by Spooky.
I've never seen an episode of Stranger Things.
I've seen one episode of R+M.
I think TV show themes are by nature fairly limited in appeal, especially these days when we all have about 6 million tv options to enjoy at any given time. it's not like the old days when there were three or four networks and a show like the Simpsons could really dominate pop culture.
A theme like R+M is perfect for a company like Spooky, as it doesn't really matter if it ever becomes a "mainstream hit" (and I really doubt it will). It's not gonna be too tough to find hardcore 750 fans of anything.