As you play Tunic, you can pick up glowing paper pieces in game. These become the "Manual", accessible from the menu. The manual was the most captivating and charming part of the game for me. It was plot delivery vehicle, tips guide, map, puzzle delivery mechanism, and made me feel closer to an imaginary player.
The first cool thing is that when you are reading the manual in-game, the game actually changes style in the background as the manual comes into focus. Your view of the game pulls back from the clean animation of the normal playview and becomes a blurry, low-res, cathode-ray tube-scanlined pixelated mess. Just as the manual recalls Zelda 2's manual with intentional precision, the contrast between game-view in the background and game-view when playing is exactly like playing an old console game. In practice, the graphics of old console games were a blurry mess. In my mind, I would fill in the blurs like I was viewing an impressionistic painting, and imagine a world as fully detailed and beautiful as the game-view when playing Tunic.
The Tunic manual has little pen scribbles in it, as if another player went through and made notes. The first time I went through a dungeon, I carefully called up the marked-up map from the manual and compared it to the game-view. It was a delight to decode the map's scribbled "x"s on the floor as spike traps in the dungeon, the doodled arrows as treasure chests tucked away. It felt like I was communicating with a past player, decoding their language so they could speak directly to me. While it wasn't helpful at first (the spike traps are obvious, the treasure chests aren't particularly obscured), it was a pleasure all the same to feel in communion with another player. Those notes did come in handy later, as a few of the more deviously hidden chests were penned in.
The manual has a little bit of the setting and background of the game in it. The pieces of the manual are placed along the linear path you are forced to travel, so your reconstruction of the manual is paced by your progress through the game. Normally, manuals are meant to be seperate from games. They come in the box, separate from the game cartridge or disk and you flip through their whole contents at your leisure with no restrictions. However, in this game, the manual is only exposed to you piece by piece and out of order. This is used to the highest effect after the Ruined Atoll. Upon completing the Ruined Atoll, there are some story revelations which play out. After the completion of these revelations, you get the manual piece which explains more of the backstory. The backstory is near the front of the manual, but those beginning pages are only revealed to you only after you have witnessed its consequences for yourself in game. The standard narrative delivery of show and tell gets more complex. You are shown, then the manual tells you, but the whole time you feel the manual has been hiding this from you. It was in the early pages of the manual, but the manual was kept from you. It should have been obvious to you if only the manual was whole. I found that incredibly fascinating.
The final part I like about the manual is that it doesn't make any sense. The manual has coffee stains on it to go with the pen scribbles. It has physical markings from coffee and pens on it, therefore it existed in a "physical" world. The manual talks about Tunic as a video game with references to SNES-style Save and Load screens that don't exist. Yet the manual is only accessible within the game, and its pieces are scattered throughout the game. The manual is critical, withholding key information from you unless you pick up the pieces. I don't believe it's possible to finish the game without some very specific instructions contained within the manual (unless you go online to read a walkthrough from someone who did read the manual). And the final scene of the good end of the game is (Spoilers here): The Hero reading the well-hidden first page of the manual, breaking the cycle you would otherwise find yourself trapped in if you didn't go through the many puzzles needed to finally collect it. The dual existence of the manual as real-world artifact and in-game guide is never explained, and I'm glad. If there's one lesson I've learned from Inscryption and The Hex it's that metatextual narratives get really boring and silly really fast. Videogames have a proud history of nonsense, from Mario's turtles, mushrooms and pipes through to taking a grenade to the face and sitting behind a wall to heal up. Things don't make sense and it's fine! Less exposition and more impressionism for me, please.