As for how I got the FPSC raw game files. Well... considering Vishnu is an ancient piece of software by now, I have no qualms about releasing the method I used. So here goes...
It's actually surprisingly simple. Instead of accessing game.enc directly... it's all about finding where the vishnu packer extracts the game files to, and grabbing them from there.
The exact folder that Vishnu Packer extracts the files to when you run it is C:\Users\username\AppData\Local\Temp\ir_ext_temp_0\XrPkTcW6V9.{20D04FE0-3AEA-1069-A2D8-08002B30309D} (the last folder may be named something different.)
Now... normally that last folder is special in that it's invisible to File Explorer (explorer.exe) entirely. But if you view the folder in an app like WinRAR or 7-Zip... you can actually go into that folder, and there you will find the raw FPSC game files... all that's left to do is to copy them all to another folder... and there you have it.