Unable to access Nexon's site or any of its games.

Hmm. By behind a router i meant connected to one. I'd delete that line from your hosts, as it's redirecting nexon traffic to localhost, which will never let you load their pages. It may fix it, it may not, but it's definitely not supposed to be there. Let me know what happens after that. You'll need to remove the line, save it, and then restart your computer. The next step if it doesn't work is to bypass the router and plug directly into the modem to see if you still can't access the sites.