Hey, there's an error on the nw.sh script file used to launch the game, you should replace all instaces of $1 with $PWD since that's how you get the current working directory. Now, to get the directory where the currently running script is place gets a bit more complicated. Also, you can set "Path" on the desktop file, which sets the working directory, so you can set it like:
Path=%k
and it changes the path to whatever %k is which would be the path where the desktop file is placed.
I hope that helps.