A sudokey and 14 messages

Question

_{This puzzle is part of the Monthly Topic Challenge #15: Multi Puzzle — two (or more) puzzles in one.} Remarks:
Feel free to post partial solutions.
This is a multi-puzzle: If you found the titular 14 messages, you are done. There is no final step to combine the messages. Though difficulty is hard to predict, I expect the east and west puzzle to be easiest. Some of the messages are hints, so if you want maximum challenge, try to ignore them.

First hints:

east-west yields the shortest paths.
east-west has part of the solution.
east-west yields the solution.
east-west has nothing to do with the solution.

The path from east to west starts small
Dawn is not a time

More hints

The layout: The center should be recognizable as (probably) a sudoku, while the other grids seem mangled somehow. This suggest that a sudoku should be solved first and used to solve (part of) the other grids.
The title (also) suggests the sudoku is 'the key'. If the sudoku is solved, consider the properties of a sudoku; and how they can be used to alter letters in a 9x9 grid, there are several; test them on the grids.

Check the labels:

Cipher: Which one of the grids has a lot of less used letters; and how could the sudoku be used to encode those letters?

Three dimensional: How could a sudoku display something 3 dimensional? Does this remind you of a game? How can you then see a hidden message?

Mazes: How could a sudoku display a maze? (mazes do not necessarily have walls; mazes are just twisting paths with an occasional choice of direction)

Extra hints:

Starting from the lower-case letter, find 2 words while going to the other side of the grid. How do the directions relate to the center sudoku?

The reference to city is because of some similarity with the skyscrapers game.

You might have noticed SUDOKU in the bottom grid, look at the corresponding numbers in the sudoku; Realizing how do they match the form of the word may help find more words.

Stonger hints for the bottom puzzle

To find the messages you need to construct an arrow maze

Transform sudoku numbers to arrows (numpad style)

find routes through that maze

map the bottom grid upon that maze to read along those routes

Answer 1

Parts 1-3 were first solved by Alaiko

Part 1

The solution to the sudoku in the middle is

Part 2

Next we should look at the eastern grid. If we read the letters on each row in the order given by the sudoku numbers (so 7 in the beginning of first row means we start by taking the seventh letter of the first row), we get this


From here, we can read the first three messages

1. THE SUDOKU IS THE MAP OF THE SOUTHERN JUNGLE
2. LOOK AT THE CITY AT DUSK AND DAWN
3. ADD OFFSETS TO LETTERS

Part 3

We can use message 3 as a hint for the western grid. Offsetting the letters by the sudoku values gives


This gives us two more messages

4. THE HIDDEN PART OF THE CITY CONTAINS AN ODD MESSAGE AND EVEN A RED HERRING
5. THE NUMPAD IS OUR COMPASS

Part 4

Next we can look at the southern grid and use messages 1 and 5 as hints. "Numpad is our compass" means that we should replace the numbers of the sudoku in the corresponding directions on a numpad.


This gives the following map for the sudoku


If we treat the 5=? as a wild card, the shortest paths from each of the borders to the opposite sides are these


Overlaying them with the southern grid gives


This gives four more messages

6. NICE SUDOKU
7. USE SUDOKU AS THE HEIGHT MAP
8. A USELESS 1
9. THIS IS USELESS

Furthermore, we should also check the unused cells


These give one more message

10. YOU EXPLORED THE UNCHARTED JUNGLE WELL DONE!

Part 5

Messages 2, 4 and 7 give hints for the northern grid. Message 7 tells us to treat the sudoku as a height map. So treating the numbers as heights, we can check which cells are visible from the west


Overlaying with the north grid gives


and reading from right to left gives the message

11. AT 5 TRY ANY OF 8 ELSE EG PATH 6 EAST

Doing the same thing looking from east gives

and


This time reading from bottom to top gives the message

12. TAKE 4 TIMES THE SHORTEST PATH

The "hidden" cells in the sudoku can be divided into even and odd numbers like this

(The blue cell is different colour because the corresponding letter actually belongs with the odd numbers.)

Overlaying again with the northern grid gives


Now, we can read the final two messages
13. SOME RED HERRING
14. EAST TO WEST N 2 S AND IN REVE(r)SE

And messages 11, 12 and 14 clearly give hints for solving the southern puzzle which we did in part 4!

Answer 2

^{Partial answer:}

So my starting point was noticing

the last row on the east puzzle.

The letters on that side can be anagrammed to "TOLETTERS". Furthermore, I realised that the numbers in the Sudoku for that row seem to be indicating where each letter in the East block should finally end up at. (For example, the 1 in Row 9 of the Sudoku appears in column 3. So this indicates that the L, which appears in column 1 for the east puzzle should end up at column 3.).

Hence, it seems if we solve the Sudoku, we will be able to re-arrange the letters in the East block.

Since I already knew the final arrangement of the letters in the last row of the east block, I can fill up the last row of the Sudoku first. By process of elimination using Sudoku logic, I got here.

This allows us to make some good progress on the Sudoku.

The majority of the last 3 rows can be then filled in as shown below.



From here, just using basic Sudoku-solving techniques will solve the Sudoku fairly quickly.

Following that,

we can now proceed to decipher what the right side reads. Rearranging the letters for each row as indicated by the numbers for that row, we get

T H E S U D O K U
I S T H E M A P O
F T H E S O U T H
E R N J U N G L E
L O O K A T T H E
C I T Y A T D U S
K A N D D A W N A
D D O F F S E T S
T O L E T T E R S

Essentially, what we have here are three statements.

1. THE SUDOKU IS THE MAP OF THE SOUTHERN JUNGLE.

This probably is a clue to solve the south puzzle, but I currently have no idea what to make of this, so let's move on.

2. LOOK AT THE CITY AT DUSK AND DAWN

I don't know what to do with this as well for now, so let's look at the last one.

3. ADD OFFSETS TO LETTERS

Ah, this seems promising. The puzzle on the west side is filled entirely with letters, so perhaps this is referring to adding the numbers in the Sudoku to the letters on the West side puzzle. Let's try that out.

Trying out that last step will give us the following for the West side puzzle:

T H E H I D D E N
P A R T O F T H E
C I T Y C O N T A
I N S A N O D D M
E S S A G E A N D
E V E N A R E D H
E R R I N G T H E
N U M P A D I S O
U R C O M P A S S

There are two statements this time round.

1. THE HIDDEN PART OF THE CITY CONTAINS AN ODD MESSAGE AND EVEN A RED HERRING

2. THE NUMPAD IS OUR COMPASS.

However, this is where I am currently stuck. I realise that there are arrows on the 2, 4, 6 and 8 keys on the Numpad and indeed, those very numbers appear once in the North puzzle. But I am not sure where to go from there. If I go through the grid in the direction each number is pointing, I don't get any readable words. Perhaps the "compass" needs to be interpreted in a different way?

Besides that, I still haven't figured out what to do with the other clues I have found.

However, I do note that the puzzle is tagged with maze and three-dimensional, which I haven't seem to make use of yet...