The company closed down, so it's almost definitely tied to that.
https://pbs.twimg.com/media/D7SrC3NWsAERNYA.jpg:large
This is a helpful chart for what is or isn't available. For anyone who doesn't have them, I'd strongly recommend getting the Sam & Max seasons, as well as Strong Bad's Cool Game for Attractive People, on Steam. Once they're gone, they're gone - they're very different from the Walking Dead, but they're hilarious games.
I'd also recommend Telltale's Batman seasons and Back to the Future - those are available physically, so there's less urgency to get them, but it seems like the only games that will exist in digital stores after Monday are the Walking Dead (on the Epic Games store) and
maybe Tales from the Borderlands.