Let first time visitors know when they come to the sight that if they have a game login then they also have a forums login.

It doesn't say it anywhere on the registration form that the forum account is tied to the game account.

BTW: you can register a longer name on the forum than you can in the game.

There is a message when you hover on "Username" field but it's clearly not noticeable enough.
Will see how we can make it better.