We use notebooks to give form to the intangible, jotting down half-formed ideas and strategies with the aim of corralling them into coherence. We record and reflect on events in our lives, a ritual that narrativises our experiences and makes them comprehensible. Notebooks are a technology, the most ordinary and unspectacular instance of cyborg enhancement – an extension of our memories. And all this makes them a fascinating motif in video games.

In Discworld Noir, a little-known adventure game from 1999, you play as a private detective named Lewton, plodding the streets of a hardboiled version of Terry Pratchett’s fictional city-state Ankh-Morpork and investigating murders and disappearances that pay homage to classic noir fiction. Lewton’s greatest asset is his notebook. Here, he writes down the names of suspects, clues, testimony and other key information. This simple device distinguishes Noir from other games in the point-and-click tradition from which it emerged.

Discworld Noir’s adventure-game predecessors revolved around item puzzles. You’d browse your inventory and try to work out which bizarre combination you needed to solve the puzzle in front of you and unlock the next bit of story. In Discworld Noir, however, the keys to progress are the nuggets of information written in your notebook. The clues collected there are your “items”. The story is the puzzle. Instead of playing with rubber chickens, ladders and keys, you play with lies, relationships, events and motives.

Facebook Twitter Pinterest Discworld Noir’s notebook helps to unify narrative and gameplay

Noir’s notebook was an elegant innovation for unifying narrative and gameplay. When we confront a mystery, we wonder about the intentions of the characters involved. We theorise and make connections. Noir’s notebook manifests your thoughts and lets you play with them – you “pick up” a clue in your notebook and combine it with another to gain new information; you flip through your notebook when interrogating suspects in order to grill them with the evidence you’ve collected and to test your theories.

It’s unfortunate that Noir’s notebook was not imitated more. Shenmue, which debuted in 1999, featured a notebook, but it functioned more as a reminder about where you should go next, offering no insight into a character’s thoughts. The 2011 detective story LA Noire contains a notebook, but it is more about reading people’s body language and facial tics during interrogations than piecing things together. A couple of indie titles followed in Noir’s footsteps – The Blackwell series and Kathy Rain use a Noir-style notebook system – but they didn’t take it much further. A couple of recent games, however, use notebooks in very interesting ways.

In the Bafta-winning puzzle game Return of the Obra Dinn, you explore an abandoned ship with a magic watch that lets you revisit the final moments of the deceased members of its former crew, whose skeletons litter the wreck. Using the evidence in your notebook – a ship’s manifest, a sketch of the crew – you must work out who these people are, how they died and whether they were murdered, in the process filling in the empty pages of the book.

Facebook Twitter Pinterest The notebook in Return of the Obra Dinn

In a game featuring a magic watch that helps you travel through time and space, you might assume a notebook would take a back seat, but the book is where you will spend most of your time, trying to organise the information you’ve collected and playing self-imposed logic games as you attempt to solve the mystery behind each death. Obra Dinn takes place on an abstract plane, where exploring information and your mental processes are far more compelling than exploring the ship itself. Here, Obra Dinn can play with the pleasure and pain of cerebral phenomena: epiphany, confusion, connection, comprehension.

If we use notebooks to express thoughts and lend them clarity, Obra Dinn’s notebook reflects that process back at you. Its incomplete notes create gaps you feel compelled to fill in. It prompts half-formed theories. You run out of mental space to shelve them and worry that you won’t be able to find thoughts you’ve set to one side when you come back for them later. But you sift through the notebook’s documents and the clues you’ve mentally stored away until you can empty it all back into the book and fill its pages with solved mysteries. It is a thrilling intellectual reward.

Red Dead Redemption 2 uses a notebook to different ends in the form of Arthur Morgan’s journal. Here, he chronicles his experiences: musing on the fortunes of the gang, lamenting the passing of comrades, sketching portraits of the people he’s met and landscapes of the places he’s been. Whereas Obra Dinn and Noir’s notebooks create a unity of thought between protagonist and player, Arthur’s journal lets us bear witness to thoughts that are not our own. We are not privy to Arthur’s inner feelings until after they have been recorded, which makes Arthur seem like a real person with his own inner life, rather than a puppet who does our bidding.

Facebook Twitter Pinterest Pages from Arthur Morgan’s notebook in Red Dead Redemption 2. Photograph: Rockstar Games

Arthur’s notebook also offers a perspective on events he would not express in the company of his Van der Linde gang-mates. Red Dead Redemption 2 puts a great deal of effort into the illusion that the Van der Linde gang is a real community whose members go about their business whether you are there are not. The journal helps here, too. When we join Arthur as he completes a sketch of the camp, his own perched feet included in the drawing’s foreground, we get a sense that the camp hasn’t just sprung into existence when we arrive to witness it.

My own notebooks are filled with scribbles, whether they be half-formed ideas or one of my tortured attempts to work through a puzzle in The Witness. Externalising these thoughts brings an almost physical relief of mental pressure, mirroring the way diary-writers like Arthur unburden themselves in their journals, or the process of untangling a mess in Obra Dinn. Flipping through a notebook – whether in a game or in real life – creates a satisfying reminder of many small mental victories.