how and where did you get the source files to mod this?
getting into the Source files of the Slenderman's Shadow maps is easy, simply use winrar to change the name of Game.enc in the data folder of the map you want to modify to .rar, and it will give you access to the source files, unfortunately from that point you have to work your way around a password if you want to modify the files within Game.enc,
While There may be some people crazy enough to buy a program to crack the password to get into the game files, they should just post in publicly, while I am one of those crazy people, if and when i figure out the password(s) I will post them if they work as a reply, while some maps might have different passwords in the entire Game.enc file, i am accessing the Elementary Game.enc file, if the password I find for it works i will post it, and do the other maps.
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I guess that's interesting to look forward to since most programs want support for their own person or group & The enc file has been locked up for years- Of course i gave up on trying to find out "how" to get access but since you're willing to use paid programs. We'll see how it goes with this much power- If there's no success it's alright