Looking more into Steve Jackson, it there does indeed seem to be many similarities, for example:
D&D : Deathtrap dungeon -> It's a trap-filled and monster-infested labyrinth where you'll compete against five other adventurers to collect certain gems, which are the key to escaping and winning the Trial.
Blood & Bones: referred to in Decarine description states: "This fabled land of gold, silver, and sacrifices owed both its rise and fall to its inhuman warriors.They applied face paint brewed from blood, giving them the strength of the gods, and carved up their own bones, crafting the weapons of the gods.Yet their legacy is neither here nor there." (meaning to me the game was not made yet). Bloodbones is also the name of one of his gamebooks, which mentions "set in the usual fantasy world of Titan ".
Steve jackson sorcery: It includes some aspects I thought about and mentioned when reading omnis hidden post: "it is possible for a reader to use the same character " complete with any upgraded abilities and equipment "
"to choose between playing as a warrior or a wizard "
Also Seeing admins post, it is not clarified if the information was false. Its best if someone (omni?) would clarify if what Asilent posted was simply guessing, or guessing with only part of insider information so we can put that to rest. I personally doubt they would take an existing IP.