So I just remembered about this series existence and wanted to try to finish at least one game. Downloaded the SWF files for games 1-3, and knowing the unpopularity and small speedrunning scene of this game, it wasn't a surprise that it wasn't archived here. So I just googled the game and used the view page source feature to download the SWF. The first website I found that I could use this on was funland.com. I will provide a google drive link here for downloading.
OLD LINK (from funland.com (TWHG4 v1.1)): https://drive.google.com/file/d/1judf1jFDLOSEvZJaUoaGStIF2w76ht-W/view?usp=sharing
NEW LINK (now on archive.org (TWHG4 v1.2)): https://archive.org/download/worldhardestgames/HardestGame4.swf
EDIT: I would like this to get posted on the resources tab for more people to see.
EDIT 2: In hindsight, I should have checked Snubby Land
EDIT 3: A version I found from archive.org (direct download): https://archive.org/download/worldhardestgames/HardestGame4.swf