The title pretty much says it all: the League of Legends game suffered a hacking attack on a couple of its European servers.
Apparently, it only happened to players on the EU West and EU Nordic & East servers, and it appears that no vital information (aka billing info) has been seriously compromised. However, it is suspected that information like user names, passwords, and email addresses were accessed. Full names and security questions may also have been accessed on a small number of accounts.
Riot Games, the company responsible for League of Legends, have taken to emailing all players to tell players to change passwords to something different and far more difficult to crack. They have also set to work on increasing security for the game and its servers. Marc Merill and Brandon Beck have also issued an apology for the debacle:
Brandon and I want to sincerely and personally apologize to you for this situation. We take your privacy and security seriously, and we’re working diligently to improve it for the better.