So... is this a scam?

"NX ID"? Looks suspicious. Maybe password cracker?

Have you ever played the game?

And who's the email from? (Email address can be spoofed, but if it's not ___@nexon.net, it's definitely not Nexon.)

He's a 7x sader, and "It's from "einquiry@nexon.net'"

I think it's legit. If they're not asking for passwords, there's no harm - people can find out login IDs just by trying to register them, so if they were a pass cracker they'd be busy otherwise. Try sending a ticket asking about it (from the ID that won), and see if you get a response in 48 hours.