ADHDers might call this a "hyperfocus" or the kind of obsession which resembles a hobby. Some activity that you think about at work all day and have to tear yourself away from to do anything else. I know it sounds like addiction, and it can look like one, but it always passes. Creative people might call it a muse?

I'm just on the tail end of one (Doom mapping), but no longer to the point I'll skip eating in order to do it. So will probably be moving on soon.

Does this sound familiar? What are your obsessions like for you? Do you get them? Have you ever had one?