This appears to be Elian Script. I'm not sure I can read the writer's handwriting entirely (and they seem to have added some nonstandard things like a zigzag for T), but the first few lines read:
?HE C PROGRAMMING LANGUAGE!
I REALLY WANT MY PEN!
Edit by OP: I spend some time to fully decipher it but I think Deusovi deserves the ...
Countries of the participants
Reverse-Engineered Ciphering Process
Now let's apply this to the original messages.
Reverse-Engineered Deciphering Process
One Last Thing To Do: Name of the Cipher
The dots in between the squares...
These can be interpreted
There are also some other ways to extract similar arrangements of letters:
The data collected:
The next step needed heavy hinting for me to find it:
Unused information [hinted to be a clue to the step I did first]:
The first thing that's apparent is that
it's natural to consider
An obvious guess is that
We then notice that
So the obvious guess is
Looking at what that gives us
Seems like we've cracked it.
In answer to the question of how difficult it is to crack,
I think this is how to place the pigs
Deusovi mentioned correctly in the comments that determining the final answer has to do with
Furthermore, as determined by Luke Bickell in the comments, applying the logic that
The grid reads