Obsidian Entertainment has laid off an undisclosed number of employees who were working on Armored Warfare, its free-to-play team shooter that features tanks, not soldiers.

According to studio chief executive officer Feargus Urquhart, Mail.ru subsidiary My.com has taken away some of the work from Obsidian and moved it back to its Moscow home base. Obsidian did not reveal how many people it laid off or if any of these employees were offered positions at My.com in Russia.

“This week we let some of our developers on Armored Warfare know that they are being laid off early next year. The publisher of Armored Warfare decided to move a portion of the development of the product to their headquarters in Moscow,” Urquhart said in an emailed statement. “We remain extremely proud of Armored Warfare and all the work we have and will continue to put into it. None of the other products at Obsidian were affected by this. We wish our people the best, and are working with them to find homes with other developers.”

Armored Core debuted in open beta in 2015 for PC. It features a similar model to World of Tanks, but instead of fighting with World War II tanks, it throws you into battles with armor from the 1950s to the modern day.

Mail.ru is a email and messaging company in Russia, and it’s had success publishing games. It recently acquired mobile studio Pixonic (developer of War Robots) for $30 million.