what do people typically do if they end up working on a game after the jam is over? Do they keep the jam project version as a historical reference for how it started and have a separate project for what was worked on later, or do you just work on the original jam project further?

I think it depends on how much you want to scale it up. A lot of jam projects end up having super messy code that works fine to get stuff done, but is very hard to work with for new features. I think making a new project is generally better but it depends on your project

i think it’s cool to keep the jam version available and left the way it is for posterity.

• a separate project page for a post-jam version is nice if you have an html build for both. that way each can be played online without having to download them. you can link to other version in the description on each page.
• itch does allow uploading multiple files to a project page, so you can use the same project page for the jam and post-jam versions. i did this with my first GBJam game. i also posted a few dev logs with some art that didn’t get used and just talking about the jam version and stuff.

ultimately it’s up to you what you would rather do. not everyone keeps the jam version available.

If I continue working on a jam and have updates to publish, I will actually replace the downloads on the original Itch page, but only because I tag my releases in source code. The source code is always included in the metadata of my pages, and I always tag the revision that was used to build and submit to the jam, and includes downloads of the original artifacts.