May be it is something small as dividing the width by 2 and setting a lower milliseconds value for the setinterval so it runs the checks more often.
Essentially this is the same solution as in the post, just stripped down to the bare minimum of code, but I haven't tested it enough. There must be some edge case that it fails on
I have a t-shirt that features the Google T-Rex Game and I found that a large number of people do not recognisee the dinosaur nor know the game despite using chrome daily!
Edit: after I did that, I discovered jsnice.org, which managed to do all the deobfuscation I did (including inferring variable names from usage!) automatically. I'm very impressed. I replaced the gist above with the JSNice output.
https://www.youtube.com/watch?v=L2NtMpQml-A