Paradox has picked up Age of Wonders and Overlord developers Triumph Studios.
Age of Wonders, Paradox says, has sold over 1m copies so far.
The current team and management will remain at the Netherlands-based firm, including Lennart Sas and Arno van Wingerden who founded the company in 1997. All on-going projects will remain in development and published by Paradox.
"Triumph Studios is a developer of our own heart," said Paradox CEO Fredrik Wester.
"They are world-leading within their niche and have built a large and dedicated community over the years, counting quite a few Paradox employees among their hardcore fans. We have great faith in Lennart, Arno and the Triumph team, and our main focus now is to ensure that they can continue to create their magic under new ownership,"
Lennart Sas, CEO of Triumph, added: "We have been approached by others before with an interest to acquire us, but this is not merely a business transaction for us. This is a liaison with a partner that can help us grow sustainably by ensuring the stability and continuity needed for us to do more of what we do best - develop some of the best turn-based strategy games on the market today. Paradox is a good match for us both culturally and games-wise. They get it. It's as simple as that, and we are extremely excited about the acquisition."