I think it would be fantastic to add support for achievement categories. Take Deathloop for example. I finished that game and then wanted to 100% it. I think I got most/all of the single player achievements, but unsurprisingly it's online mode is effectively dead, making it impossible to get the related achievements. It would be a great boon for developers to be able to categorize achievements so I could still get my 100% badge on that game...at least for that category.