This Opinion Angband package has been patched so that all writing is done in the /var directory. Specifically, the following:
/var/games/oangband/data
/var/games/oangband/save
/var/games/oangband/apex
/var/games/oangband/user
If you're making data backups of your system, the /var/games/oangband directory would be a good one to include.
The file init2.c is patched; the patch should have been included in the same directory as this file.