The free game works on iPad, iPhone and iPod Touch devices. Players "roll" the Lego dice to pick one of four categories - nature, vehicles, buildings or things.
Players must then build an object from that category out of Lego bricks, and players guess which of the four possible answers is correct by tapping an illustration. The faster players guess correctly, the more points they earn. Scores can be shared with friends via email or on Facebook.
The mobile version of Creationary features 100 models at launch in infinite play combinations, and the firm has plans for periodic and seasonal model refreshes.
Michael McNally, brand relations director, Lego Systems, commented: "Lego bricks, whether in physical or digital form, provide hours of shared family fun, and mobile devices are a perfect way to take Lego play on the go.
"More than 2.5 million people are using our Lego Photo application, so we were inspired to celebrate the success of our new Lego board games with another app that brings Lego bricks to life in an entirely new way."