And it wasn’t important enough for him to list on the standalone games pages.
Now, Prophet Shooter is unambiguously anti-religious, so maybe there’s something there? And he’s got a Trump parody game. I’m not 100% sure here, just leaning against it. It’s also certainly true that sometimes extremism is the result of mental illness looking for some kind of framework to cling to.
Note that the dates may not be accurate; according to a quick bit of genealogical research, his grandmother Paula married his grandfather in Bavaria in 1955 < https://www.genealogy.com/ftm/b/i/s/Robert-S-Bishop/BOOK-000...>. Could also be that she left Germany and then returned for the wedding, of course.
Paula’s mother’s surname appears to have been Ketzler, which doesn’t tell us a ton about ethnic background. Not that it would tell us much about the attacker in any case, even if that was why she left Germany.
Edit: he had at least a bit of 4chan activity, as per his journal.
Recalibrate. It's overt.
This person is gravely mentally ill, though.