Save File for The Impossible Dream and another 1 for Sequence Breaker.
Link & Location
Back up your own save file first
Both save files are modded to have a lot of resources (Money/Cogs).
1. File can be found at C:\Users\(user)\Documents\My Games\SteamWorld Dig 2\(steamuserid)\
2. Download save files from:
https://www.dropbox.com/sh/h3kyzhgagxih7eh/AADJdHH5KiIDTp2Qr7a9ZkpDa?dl=0
3. There are 2 save files, “savegame_001” gets you the Sequence Breaker achievement and the “savegame_002” gives you The Impossible Dream achievement (and the other 4 golden category achievement if you haven’t gotten those yet)
4. Paste the save file that you need.
5. The 1st save file puts you in the cave where the last remaining generator is, just break it and the Sequence Breaker achievement should pop.
6.The 2nd save file spawns you by the tube in Oasis, just walk to the right of it and enter the giant gate to fight the final boss Rosie, I recommend watching guides on how to fight her because it can get a bit messy, even with all cog upgrades enabled it still took me 4 attempts to beat her.
7. After beating Rosie, go finish the post-boss fight sequence, and let the credits roll, after that, The Impossible Dream achievement should pop.
Thanks to Izayaa for his great guide, all credit goes to his effort. you can also read the original guide from Steam Community. enjoy the game.