If you want medals and scoreboards for your Unity game, look no further.
https://github.com/AdamRVierra/NewgroundsAPIUnity
Feel free to report any problems that you experience, it's still a work in progress. Included is an example scene on how to interact with the Newgrounds API. There's documentation included as well that serves as a step by step guide on how to get medals hooked up.
I also encourage others to help add support for the rest of Newgrounds functionality. Most notably save files and the other unfinished functions that show up in the example scene. So if you think you can contribute, go give it a shot!
MSGhero
If you need help with save files and the encryption process, I did that here in haxe: https://github.com/MSGhero/NG.hx/tree/master/src
Though psychogoldfish told me they were gonna change some of that in the future.
Coolboyman
Thanks dude, I'll have a look at that later.