Walkthrough

Prota
At the beginning, you're practically handed the key to Prota to start your journey. To get the key to the next zone, and additionally, the flowers, you'd need to do some simple puzzle solving.

For this first puzzle, there's four books on pedestals presented to you. The books start by telling you a specific number for the first puzzle, the symbol on the pages and the 'password' key on the nearby counter shows you the shapes in what order their numbers need to be put in. After that, you would need to re-arrange the dolls on the pedestals of the correlating color.

In a previous version, you would've needed to grab the flowers to continue, but from future confusion of some of the players, the most recent edit made it so now the flowers are an optional item to acquire.

Additional:
 * After confronting Seiko (after the second time) in Achroma, you may backtrack to find her in one of the houses in Prota.
 * After "the decision", you may backtrack to discover a small box displayed on the counter.
 * Also after "the decision", you may discover a new book found in the same house Seiko was in, which wasn't present in the previous version.

Trita
Trita is a breeze to pass with hardly anything tricky presented to you. After riding the train, you have to do an easy button-pressing puzzle. After finishing the puzzle, the optional flowers are presented to you and the key will be found soon after leaving and teleporting back to the room before the train ride.

Additional:
 * A nifty, though a bit depressing, little interaction with the creator's persona can be found by inputing the game's release date in as the code to one of the locked buildings.
 * In the hallway with all the buttons after the puzzle, there's an entrance to a secret area located in the middle of the second group of buttons at the bottom.
 * After confronting Seiko in Prota, you may backtrack to find her in the now unlocked building.

Deutera
Once you arrive to the distant island by boat, there's a bit of a maze puzzle presented without any sense of direction other than the volume increasing before stepping through the right path. When it shows only one door, that means you reached the end and can now leave. You will not gain flowers or the key from this.

The real puzzle is activated after you're requested to find a necklace and are promised the key in return. If you try to progress to the puzzle before the request, spikes will block your way.

This puzzle is set up to trick players by pretending like the numbers on the plaques are the numbers for the code, though, the real code is whispered from the lower chamber of the area. Because of mentioned issues with this code, the whisper is repeated once with emphasis on the numbers before the event is deleted. After that, you're presented with the flowers before you complete your goal, but once the right code is put in and you get the necklace, you just need to hand it to the one that requested it to get the key in exchange.

Additional:
 * In the lower chamber with the whispers, you go almost directly across from where you entered the area (but one block down) to enter a secret area.
 * After confronting Seiko in Trita, you may backtrack to find her on the island.

Achroma
While Achroma is built more isolated and restrictive than the other areas, it makes it so the player won't get stuck in an area without the items needed and have to restart from a previous save. The items needed are easily available, some after specific events happen, and push you to take them to continue to the puzzle. Achroma's puzzle is also pretty easy with only needing to match the room's symmetry as long as you don't mess up pushing the bin into a corner and have to restart to fix that.

When you're done with the puzzle, you just exit the room and are presented with the flower to show that you officially finished the puzzle, but the urges gets the best of the character and you reach the top of the final area before plunging into the void.

Additional:
 * In the right building, there's a asymmetrical bit of the floor (compared to the left building) and it's then removed to reveal a secret room beneath the building.
 * In the district building, there's rooms on the left you can enter and interact with the center of the rooms to then be teleported to a secret room where you then can interact with a musicbox repeatedly.

Void
While it may seem much like the end, there's still choices and codes to figure out. Will you side with your most heavenly or your most hellish side? Once seeing what comes from either of these two, you then come across some otherworldly god-like beings that seemed to have been represented throughout the other parts of the game. Now, this is where you count all the blinking eyes you see in the parallax.

Once you've got the code figured out, then you go ahead and do what you must to activate the ending. This is where "the decision" comes into official play.

Apart from that, this is only an event activation and does not alter the endings of the game; and this game doesn't have an official "true", "neutral", or "bad" end that's typically seen in these types of rpg games.