I don’t know about you, but for me, the most problematic—or rather, grind-heavy—achievement in Astral Ascent was "Synesthesia", the one where you have to collect all paint colors for the character Oloon.

You can get the tickets needed to unlock them by clearing Research Rooms — and only those. Moreover, not every room will have Yali with those cursed tickets.
Personally, it took me 20 hours to farm all the tickets.

That’s why I’m sharing this guide and providing my save file, so anyone who wants it can get this achievement without enduring hours of grinding.

WARNING!
The author is not responsible for any potential save file issues, so before placing my save in the game folder, back up your own save in a different directory!

1. Download the file "aa_game.sav_oloon" from the folder:

Yandex Disk: https://disk.yandex.ru/d/UejUorr2icgfqQ

Google Drive: https://drive.google.com/drive/folders/1PP9M_b_nkFAaWUZs19mKsP6LZ0BxQQPu?usp=sharing

2. Navigate to the path: %USERPROFILE%\Saved Games\Astral Ascent, then proceed to the next folder (which will be your user ID).
There, you’ll find the file "aa_game.sav".

3. For safety, copy the "aa_game.sav" file somewhere else as a backup.

4. Place the downloaded "aa_game.sav_oloon" into the same folder (%USERPROFILE%\Saved Games\Astral Ascent\<user-id>\).

5. Rename "aa_game.sav_oloon" to "aa_game.sav".

6. Launch the game.

7. Approach Yali in the cauldron and collect Oloon’s final color.

8. Profit.

Hope this helps those in need!