Tunic is an isometric action role-playing game that sees you traversing a wide array of landscapes in search of clues, chests, and ways to unlock the great Mountain Door that rests on the farthest summit. Reaching the latter, however, involves having to solve a certain puzzle: The Golden Path.
The Golden Path is a puzzle made up of a set amount of squares on page 49 of the manual. Acquiring this page of the booklet gives you the opportunity to see the grid and, in turn, solve the input code needed to unlock the Mountain Door.
To solve The Golden Path puzzle, you will need to collect every page shown on the grid, found on page 49. These can be found when progressing through the main story, usually in chests, around bosses, and in hidden locations. Collecting all corresponding pages is an essential step in solving the puzzle.
Once the pages have been collected, you will need to cross-check each page as seen in the grid on page 49. Each unique page will have one or two lines which, when put together with all other pages, forms a complete diagram. This will give you a series of directions which can then be used at the foot of the Mountain Door. Note that the door will flash purple if you have entered the correct code.
If you are successful, then you will be able to ascend the steps and unlock the true ending.
For more Tunic content, check out How to open the Mountain Door in Tunic right here on Pro Game Guides.