: If you got even a single grind badge while this was active then you should have had it unlocked.
!COMMUNITY CHALLENGES CAN TAKE UP TO TWO DAYS TILL THEY UNLOCK!
I assume as with the last challenge that this won't show our progress:http://www.insomniacgames.com/community/showthread.php?57939...
You'll need to play some of the story missions in order to unlock the ability to get badges.
Once unlocked, simply grind on any rails or wires to get awarded a badge.
Unsure if under-grinds on wires count towards this. Probably not.
You must change rails for progress to go up, I tried setting myself on a small circle rail in hopes I could leave my system on at night while it grinded (pun unintended) badges but no go.
Video of how you should be trying to go for progress on this:
You'll also unlock the current solo challenge if you haven't already and you make the counter go high enough.
Likelyness that we'll reach the goal is pretty low.