1. Download saves from bellow link (remove space).
   
   https://www.mediafire. com/file/299rsovzhb35ed0/Downfall_-_ending_saves.7z/file
   Saves are compressed with 7-zip because of size (20MB a piece).
   
2. Extract them here (copy&paste into explorer address bar)
   %UserProfile%\Saved Games\Downfall (2016) Steam
   (folder should exist if you played already, if not - create it)
   
3. Run game and load save you need.
   
4. Activate "Lever" in-game. That's it.

Also included is Normal ending if you are curious to see yet another different slide.
All three saves will additionally unlock Auto-Saviour and Hardcore achievements.

* * *

Do note saves are made and will ONLY work with 1.1.3 version of the game. That is the nature of the beast (Adventure Game Studio) I'm afraid as saves become incompatible between versions.
Should Downfall get updated sometime after this guide, you could try and find v1.1.3 to replace your installation. Maybe developers themselves will provide previous versions so earlier players are able to load their saves, who knows. Check under BETAS drop-down before anything else.