Employees working on the highly-anticipated video game Cyberpunk 2077 will be forced to work a mandatory six-day week to hit its release deadline.
This contradicts a previous pledge from the studio not to impose a so-called "crunch".
Polish developer CD Projekt Red told staff mandatory overtime would be introduced in the weeks leading up to the November release of the game.
The company said it was "one of the hardest decisions" it has had to make.
Last year, its chief executive had promised to allow staff to opt out of extra hours.
The announcement comes after months of delays to the game.
Cyberpunk 2077 was originally scheduled to launch in April, but the date was initially pushed back to September, and is now due in November.
"These last six weeks are our final sprint on a project we've all spent much of our lives on," said Adam Badowski, head of studio at CD Projekt Red, in a post on Twitter.
"The majority of the team understands that push."
Some staff have already been working nights and weekends for more than a year, one anonymous employee told Bloomberg.
"Starting today, the entire (development) studio is in overdrive," Mr Badowski reportedly wrote in an email to staff, adding that the overtime would amount to one extra day each week.
"I take it upon myself to receive the full backlash for the decision. I know this is in direct opposition to what we've said about crunch.
"It's also in direct opposition to what I personally grew to believe a while back - that crunch should never be the answer. But we've extended all other possible means of navigating the situation."
According to Polish law, a standard working week is 40 hours within five working days, which amounts to eight hours on average per day.
However, there is an exception to this rule if the employer has special needs.
Mr Badowski said employees will be "well compensated for every extra hour they put in", as required by law.
In recent years, developers have been criticised for overworking staff - often with no additional pay - in the run-up to a game's release.
Dubbed "the crunch", it's something major companies - including Electronic Arts, Rockstar Games and Epic Games -have all been accused of.
Last year, Marcin Iwinski, CD Projekt Red's co-founder, and Mr Badowski, promised to avoid over-working staff, as they wanted to make their company a more "humane" place to work.
"We are known for treating gamers with respect," Mr Iwinski said to news website Kotaku.
"I actually would [like] for us to also be known for treating developers with respect."