Thank you for sharing the source in the first place.
I personally prefer projects/libraries with more permissive licenses than AGPL.
In terms of reinventing wheels… you precisely told why people do that: learning an engine. I’d use it to create an offline version of my favourite card games, but also, how to discover others think during game development. Latter for me is also important if I’d like to understand mindset how to create things more effectively.
About support… it’s actually hard to say what do you want to achieve. Making an app, library, a game by yourself? Sharing achieved results with community? Find others who can enjoy to create a game in a team with less requirements as there’s in companies?
Does it still work?