All's well, mate.
I realise that you were asking for suggestions and my pot was not entirely on point. As such, I can see how you could have seen it as self promotion instead, however, the fact of the matter is that I read your post and I uploaded that entire package to this site especially for you. Heck, I don't think I even posted an announcement here in the forum to tell people the asset is on itch... It's available to all, sure, but I uploaded it for you. Buy on the Asset Store or download for free here... trying to be a good neighbour :) That is why I was so upset by the apparent spit in my face with your reply.
Anyway, we are on the same page now and all is well. As for GameSparks, yeah. I refer to them as Sparks or sometimes Sparky. I do that so often that I often forget the full name :P My Bad :P The way I look at them, they basically do everything a person could want and if only I didn't have such a hard time getting their API to work I would have used them for everything and recommended them to everybody for anything. When it comes to "features" there are few websites that make me fall in love every time I read them... Oh such lovely words ... all those features with the word "free" mixed in between... I think I'm going to faint... ;) So if you are asking "what features should I"... I can usually stop reading right there cause I already know what my answer is going to be: "Just do whatever GameSparks does and you will be golden" :)
Not sure if that was helpful but that is my opinion non the less :) Good luck with your tool
Peace out