Bravely or not, I installed Games on Moodle 3.2. It was the only essential plugin not yet updated. After installation, I had to change the permissions from the control panel and it works.
However, just found a bug. Old glossaries aren't deleted from the plugin "memory" despite having been deleted from a course and caches purged. Asa result, this has multiplied the number of available categories (one from each former glossary). Of course, if a glossary no longer exists, this leads to an errror. My solution has neen to change glossary names so I can distinguish the latest glossary from old ones. Has anyone encountered this issue?