DC Universe Online has seen a 1000 per cent increase of concurrent users since going free-to-play on November 1st.
The superhero MMO, managed by Sony Online Entertainment, has also gained 330,000 new players since the switch from a subscription model.
The 1000 per cent rise suggests the game had about 30,000 active users before turning free-to-play.
“We are over 1000% of our pre-F2P concurrent numbers. We're very aware of the long queues and other issues. We're on it,” said SOE president John Smedley on his Twitter account.
Servers for the title have struggled to handle the large influx of new users, with issues such as lag and login issues being reported.
Sony Online Entertainment recently said the decision to make the game gratis was “absolutely not” a response to falling subscriber numbers.
DC Universe was released in January this year, and charged customers $15/£10 per month.
The MMO can also be downloaded on PS3 via the PlayStation Network, though it weighs 25 gigabytes.
Virtual items that can be bought within the game will fuel future revenues.