Digital Extremes took to its forums on Wednesday to warn players of its free-to-play shooter Warframe that its servers had been hacked and thousands of email addresses had been exposed.
"Last week we were made aware of a potential web server breach that occurred in November 2014. At the time, we believed this to be a phishing scam as our account server was secure. After a thorough review of the data we received, we can confirm that a list of 775,749 email addresses were acquired through a Drupal SQL exploit that was patched by Drupal two weeks after the breach occurred," it said.
"The stolen data DID NOT include any account passwords, variations of passwords, hashed passwords, game account data or personal player information such as full names, addresses or other billing and payment information."
It also warned players to be careful of phishing scams and to update their passwords regularly.
"As part of our continued efforts to improve the security of Warframe, over the last year and a half we have added two-factor authentication (2FA) and also replaced Drupal with a custom website system that no longer stores any account information to avoid exposing ourselves to these sorts of attacks."
Warframe is playable on PC, PlayStation 4 and Xbox One and recently indicated to PC Gamer that it was seeing around 100,000 peak concurrent players across all platforms each day. It has 26 million registered users worldwide.