I think the first co-op game I ever played was Myst back in 1993. It wasn't technically co-op, but my friend and I treated it that way. We sat side-by-side at my PC, playing through the point-and-click adventure and working to solve its baffling puzzles together.
Blue Prince, a game where you enter a strange, shifting 45-room mansion to find its hidden 46th room, has a bit in common with Myst: it's about exploring an eerie and mysterious location, you'll need a pen and paper to take pages of careful notes, it's perfect for playing alongside a mystery-loving partner or friend… and it's absolutely packed with intricate puzzles.
