IO Interactive is "working around the clock" to fix a bug in the Xbox 360 and PlayStation 3 versions of Hitman Absolution which causes players' save data to become corrupt.
VideoGamer.com first reported on the bug last week, which wipes the player's save data following a random crash.
Multiple Xbox 360 and PlayStation 3 players are reported to have suffered from the bug, with some claiming to have lost hours of progress as a result.
Publisher Square Enix says that a fix for the bug is its "top priority", but hasn't disclosed the cause of it.
"We're sorry for the frustration this is causing for those affected," wrote a Square Enix spokesperson on the game's official forum, "and we're doing everything we can to get it sorted as quickly as possible.
"I'll come back with updates as I have them."
The spokesperson added that "any fix would be via download", but chose not to provide an ETA on when the fix would be available.
In response to the post, one user called the glitch "disgusting".
"It's bad enough this critical error wasn't addressed before release, but now its [sic] a massive group of dissenters waiting for a patch 5 days later!" they said.
"Unacceptable, i've lost so many hours giving this benefit of doubt, it's painful, silent assassin rankings and everything deleted 2 levels to the finish, I am returning this game and never buying another Square Enix product again."
Another asked whether "ANYBODY [KNEW] IF GAMESTOP WILL GIVE A FULL REFUND FOR THIS PIECE OF CRAP EXCUSE FOR A "FINISHED" PRODUCT?"
VideoGamer.com is still awaiting an official response from Square Enix.