it does say i already have it
can you try installing the source zip again? then just extract all to a folder, and run the .py script from that folder, dont take it out or put it in an editor as it might not work. The reason for this is that my code assumes all assets are already in the same directory (folder) and the script, if they arent itll crash.
You said it gave "slkscre.ttf missing" error, if youre running the script from the folder it should open up a console and close it as it crashes. If you managed to read the error somehow you arent running the script from within the folder.
alright I have no idea what might be causing this, try this last thing, you said you has slkscre.ttf on your pc, maybe the file explorer automatically chose not to copy it again, so try copying slkscre.ttf to the game folder
if this doesn´t work all I can recommend you is to get the .exe version, you can still read the script, and it has a script on this non-source version as well, but only the .exe will run