I will be creating a piece of (probably) commercial closed source software. It will be a web game. I hope to use some software that is GPL licensed, like nodejs or express(js). If I make minor changes to these frameworks, mostly to change a small behaviour I do not like, do I have to publish that change? Also can I include unchanged software in my project?
None of this is being distributed, it will only serve pages to clients.
If the software runs entirely on your server, it is not generally considered to be "distributed" (for GPL v2) and is certainly not "conveyed" (for GPL v3). That excuses you from all GPL requirements. There is a different license (the Affero GPL) which does apply to use on your own server communicating with others, but that was written precisely because the GPL does not apply.
This is the interpretation adopted by the FSF, who wrote the GPL. See their answer to this question here.
