Had to change my post!
You may be tried to laod the file by right klicking it.
Thats NOT the way it works.
You loaded a HTML-Document.
I make a little note for normal users 
(sorry I am way to familiar with this stuff to think this could be a problem
There is a script in the other thread I linked. You can even change it to use the python script @bison created. I would rather suggest that you wait for the updated deb/tar.gz that will be released soonā¢. Whatever you do I strongly suggest not running software with gksudo/sudo if you donāt know what you are doing. It runs the program as root, which is neither needed in this case nor helpfull.
Check here for when the new linux version is released: New version being worked on
NEVER use sudo when you dont know, what the script/program does.
Anyway, I followed your āsuggestionā and the scipt can launch the game, when it is in the same directory.
See modified README for details
thanks for using my dirty fix ^^
The game is so damn much fun that I could not wait and I could not let others wait.
Thats why I made it.
Currently adding more features to my workaround scriptā¦ whats going on?!
Maybe a misunderstanding here. My response was mainly for @Tisse. Only linked your name inside it so he/she knew which python script I refered to.
Btw. if you are bored you could even let your script repackage the game with the renamed image file the way @jon mentioned in the other thread.
Thats a little bit oversized.
I mean, the patch is on the way (with other bugfixes!) and it is a whole lot harder to figure out, what I have to do with this *.pak file, or repacking the files back into somewhere and so on.
And it is not like SimCity where they had to rewrite the whole game to get these āheavyā calculations back to the desktopā¦ I mean to change 2 LINES of code to break the always online DRM.
"ā¦ rewrite the whole game my assā¦ "
Sorry, I were a SimCity fan back then.
So my point is, thats not really needed
Uhm ā¦ no, it isnāt. If you read @jon post and the site he linked he tells you exactly what to unpack. I just guessed you were bored because of your previous statement:
Just for shits and giggles, get the tar.gz file from your payment link, unpack it, change into the directory and then:
unzip -d gdt gamedevtycoon
cd gdt
mv images/superb/level2Desk.png images/superb/level2desk.png
zip -r ../gdt.nw *
cat nw gdt.nw > gamedevtycoon
chmod +x gamedevtycoon
rm -r gdt gdt.nw nw
Aaaaand if you even want an updated version of node-webkit you first go to node-webkit on github download the appropriate version (32/64 bit, linux) unpack the fles into the same directory you unpacked the tar.gz in and after you ran the commands you even got an updated node-webkit.
Looks like you know already how to do it ^^
So, why not just doing it?
Iām lazy aaand with your py script you could probably go even more over the top. Checking which arch the script is run on, downloading the fitting node-webkit automatically, etc. 
We have updated the packages. Please try them out:
http://forum.greenheartgames.com/t/linux-v1-3-8-updated-packages/2681
Thanks