Why did you make this?
It seemed like a fun idea and was interesting to code - it’s not every day you get to design something to work with 5 million or so builds.
Is every build shown actually unique?
Every build shown is guaranteed to be a unique combination of perks and that combination is guaranteed to not appear again for at least a few hours. After that period it’s thrown back into the pool and has the same chance as everything else of appearing again. Given how many there are, there’s a decent chance you won’t be seeing a given build again for a while.
How does this work with match sharing?
The builds of any friends you share the match with are taken into account. If they’re unique, they’ll be counted.
What happens if my friends and I run the same build?
If you each upload the screenshot, whoever upload it first will “claim” it. If you share it with match sharing, the uploader gets priority, after that it roughly follows the order on the scoreboard (in the case of builds you didn’t run but multiple friends did).
Is there any sort of reward or prize for being on the leaderboard?
Other than having your name appear on it there isn’t currently. I have an idea for something cosmetic I may implement in the future but beyond it’s just meant to be a bit of fun. Maybe I could change this if I receive any requests or cool ideas 
Why didn’t I get credit for a build?
Either you or someone else must have run the build already. Only one person across the whole of NightLight can get credit for a build, once someone’s played it that’s it. If you think your build is genuinely unique or crazy enough that no one will have ever run it and it still doesn’t count then feel free to let me know and I’ll check it out for you.