You are right denost!
I didn't play the whole game as intended (sorry to (maybe) disappoint you Janaba but thanks for your message

). I'm still missing a lot of stuff especially in the 3rd part. It's hard to understand but I'll try to explain nevertheless.
Start to Eternal Snow Summits Island:From the start to the point where I reach the island with eternal snow summits, I'm doing all the things that were intended by the scenario. I'm missing nothing, everything flows.
Eternal Snow Summits Island and the surrounding areas:Once on the island with eternal snow summits, I understand the logic of this whole area, I just cannot solve it. And this is where another kind of logic jumps in: skydiving to cross barriers. You have to have a deep understanding of the whole age logic to be able to "sneak" your way through like I'm doing. I found an interesting note somewhere (unreachable for me), I just took a picture and I studied the whole thing. It says: "B1 B2 B3 B2 B4 B1". "B3" is impossible for me, it's just unthinkable... "B2" for me is avoidable, I can easily go around either way so no need for me to play with it. So, I'm solving it like this instead: "B1
B2 B3 B2 B4 B1" --> "B1 B4 B1". Obviously doing it like that, "B4" is completely out of reach... but is it really? I found a breach, I was stuck on the wrong side of a collision wall, all I needed was a "hole" and the "hole is provided by a subworld, the lift, on the clue island. Everytime I want to cross from outside to inside, I just need to wait for the lift to come back down and jump literally through the "hole" it opens. After that... well I'm on the clue island

I do my stuff and that's it!
I then go for the sliding door island. The barrier is open (because of "B4") but not the access to the island itself... Is it bothering? Hmm no! I sneak my way there, in and out, using skydiving, I do the stuff I must do. I've just been very lucky the first time, I got the action right, the location right! So, once there, I go directly to my favourite spot, wait like a predator on its prey, and Paf!!! Voilà! I get the intended action all the time within minutes. This action enables me to push further down the journey normally
Beyond that:I go to the last locations normally and play them the intended ways up to the end part.
-------------------------
How I figured out the coordinates of the last puzzle? In reverse & with luck

.
I had the clues (clue island) & the pictures of every coordinates I took during my journey on one hand, & also the mathematical operations that Gary Bradwell left in different locations on the other hand. I couldn't get the solution though; I'm not really into mathematics solving... I went to the said location, I tried something, anything,... plouf I was in the water! Ok that was obviously not the good solution... I stayed right in front of the imager going through all the coordinates, and I luckily clicked on the one I found the most appealing, I had no idea what was the solution. That time I didn't plunge in the water so I figured it out, I got it right. I only did 2 plungeons

before I got it right.
-------------------------
From that moment forward, everything is easy. And I can find back the solution in reverse now since I have all the original coordinates, all the clues, all the notes, & the solution (I was lucky on it but I found it nevertheless).
Here's "Annabelle's method"™ to complete an age:1) I'm solving what I can solve
2) I'm filling the holes with skydiving
3) I'm backtracking the adventure to understand everything <-- I might not do it right away with Elsewhere
I did it with Somewhere, Iceworld, Elsewhere, Adrael, Elodea, R'Oshanhnin Korvahkhn, etc.
A walkthrough coming up?Not really, because you'll have to do skydiving as there is at least one puzzle I'm skipping: "the colour dots puzzle". I just cannot understand it at all. This is why I'm saying, I need to have a deep understanding of the whole age logic, because I need to figure out if what I'm skipping, the said puzzle, will impact the future or if I can jump right back inside the story quite easily... I know I'm missing some stuff, I saw a strange location with a strange device, I have no idea what it does... Gary Bradwell refers to it on a note left near the coordinates imager on a faraway island.
So yes I'm missing some of the intricacies of the whole age but I'm still enjoying my journey there very much!