I find my brain extremely happy when a game provides ample opportunity to make connections, like in Dwarf Fortress, where I watch an event unfold, which can stir my creativity and imagination like nothing else. Writing a story out of it is extremely smooth and easy compared to other sandbox games.
I also find myself in love with immersive sims like Desu Ex and Thief, where level design and exploration take a front seat, every map is like a big playground with verticality and branching paths, where you find secrets and lore hidden around every corner in an atmospheric world.
What is immersion to you?
The only quality that matters is that sweet sweet dissociation. When I lose track of time in Rimworld and suddenly its midnight, thats immersion to me. When the controller rumbles in skyrim, thats the opposite of immersion because I feel my own hands touching a controller and am reminded I exist.