Epic Games has warned customers that their forums have been “compromised by a hacker” and advised users to change their passwords if they are shared with other websites and services.

A notice of the security breach was sent out to users via an e-mail, which states hackers may have “unauthorised access to usernames, email addresses, passwords, and the date of birth provided at registration.”

It also details the specific forums that were hacked: “The affected forum site covers UDK, Infinity Blade, Gears of War, Bulletstorm, and prior Unreal Tournament games.”

Separate forums covering Unreal Engine 4, Fortnite, and the new Unreal Tournament “were unaffected.”

“We apologize for the inconvenience this causes everyone,” the email continues. “To further understand what’s happened and prevent it in the future, we’re working with a computer security firm to identify the nature of the compromise. We will report further information on the forums when they reopen.

“It is possible that any information stored or sent by you using the forums may have been accessed. Since this is a public forum, we do not collect or maintain financial information, but we advise you to be alert for suspicious email such as phishing attempts.”

Epic Games’ Fortnite combines first-person shooting, base building, and tower defense. The title has been in a closed alpha state for months now, but no official release date has been announced.

In May 2014, Epic Games announced a new Unreal Tournament game was in development. Powered by Unreal Engine 4, the title will be free to players. The studio has stressed that it is not free-to-play, but will be supported by an in-game marketplace where users can create and sell content.