I think it mostly felt less polished due to things like the lack of music and the fact that Go itself is a bad language for this sort of thing.
In Untrusted, there were often places where you could monkey-patch objects and come up with really creative solutions. There were some problems that I felt like I really had freedom to be creative.
In this game, the imports were always out of bounds for editing, so I could never pull in 'unsafe' and have any real fun. All the solutions felt far too restrictive. Sure, there were multiple ways to hack around things, but it never felt like there was room for a spark of real creative joy.
I think go is just a bad language for "fun". It's not optimized for being able to write interesting or elegant code. It's not optimized for having fun.