Germany’s InnoGames has raised a round of funding from Fidelity Growth Partners Europe to expand its business of making browser-based games. The amount of the investment was not disclosed, but the company said it was in the “double digit millions.”

The Hamburg, Germany-based company was formed in 2007. It has since grown quickly to more than 50 million registered players worldwide on the strength of hits such as Tribal Wars, The West, and Grepolis. All are free-to-play online games, where gamers can play them for free but pay real money for virtual goods such as better weapons.

Fidelity Growth Partners Europe made the investment from a new $147 million fund, which was announced in January. The fund is focused on venture and growth equity investment in European tech companies. InnoGames’ founders are Eike and Hendrik Klindworth and Michael Zillmer. Rivals include Bigpoint and GameForge. InnoGames most popular game, Tribal Wars, has 32.5 million registered users. The company publishes in 33 languages and has users in more than 200 countries.