That is your belief. I could release content (textures and level
geometry) that I have been creating for my game right now, and it could
be used by at least 6 other game engines, and a variety of utility
programs.
They could be refactored to work with other games, yes, just as code can be (and is) refactored for other works.
In general, for game content to be meaningful, it must be designed/packaged to certain specifications which make it clearly intended to expand or extend the existing GPL-licensed work.
Your engine is special. I've looked at it, and your engine isn't AGPLv3,
it's AGPLv3 + additional clauses.
Quoting from your license
<-- start quote -->
Did you check the source code to see if any additional clauses were added to the AGPLv3 before making this claim? Apparently not, and neither did
Francesco Poli a little over a year ago when he made similar accusations based on text on the same URL:
http://www.mail-archive.com/debian-legal@lists.debian.org/msg37427.html
Again, a reaction to content on a wiki page without bothering to read that no "extra clauses" were ever applied and have never appeared in the svn trunk nor any release. As I recall, the "License" page wasn't even linked to from anywhere on the site at that point and represented internal discussion only until it was posted to this list and I had to mark the page as readonly to stop the barrage of wiki edit flames coming from readers of this list.
To put that discussion in context, we had already resolved with a lawyer that no extra clauses were required to achive the desired effect and would thus be redundant, but nobody here bothered to ping us about this even to verify that the content of a wiki page was actually edited by one of us.
Yes, I am upset this is the second time someone has made unfounded and unresearched claims on this list regarding "extra clauses" being applied to our software, and a good example why I'd prefer if Debian not have anything to do with our project.