Social game developer Wooga has announced that it has topped the 20 million monthly active user level, which not only makes it Europe's biggest social game developer, but also the fourth largest on Facebook worldwide.

Wooga is best known for its addictive action-puzzle games, like Bubble Island and, more recently, Diamond Dash, with its most popular titles suprassing the six million MAU mark.

"Capturing 20 million active Users in just 20 months and surpassing Playdom to become number four in the world is a stunning accomplishment," CEO and founder Jens Begemann said. "We will remain focused on producing high quality games with a unique game experience for the future.

"With our ambitious team, we aim to become number two by the end of this year."

Currently EA/Playfish ranks in at number two, with over 37 million MAUs.