It's just made in puzzlescript: https://www.puzzlescript.net/
There's a link to the game's source in the description if you want to look at it. I copied it below:
https://www.puzzlescript.net/editor.html?hack=4726d7d18cd855627898f26e70babf77
As far as expanding it, maybe if I had a good idea of where to go with it. But I'm currently in the middle of a major project already so I don't really have time to take on something else. :)