In case you take it up as a retirement project: what I'd love to see is an avatar builder's kit. Create the core engine, a basic level, monster, item, and class editor, and let people mod it. The basic party mechanics and att/def model could be standardized, but let people create their own game based on their own data. Create the hooks for people to add additional gameplay (ingredients, etc). Let people self-host.
Like you, I think about doing this every couple years. :)
Like you, I think about doing this every couple years. :)