If I told you Trivial Pursuit and Frogger were the hottest things right now, you’d most likely assume you had fallen through time. But that is exactly what is happening — well, sort of.

Trivia Crack and Crossy Road were among the top downloaded iOS games of December, according to industry-intelligence firm App Annie. The Etermax-developed Trivia Crack shot up the charts last month as it spread through social media and word of mouth. Trivia Crack is a spruced up version of the classic board game Trivial Pursuit where you must answer questions from six different categories in a battle against other human competitors. This old-style game has found a new audience thanks to Etermax integrating connected features like Facebook and notifications. Mobile gaming neared $21 billion in worldwide revenue last year, and upstart games like Trivia Crack played a big part in making that happen.

“The combination of social integration and engaging gameplay helped Trivia Crack surge on the iOS App Store in December, particularly in the U.S.,” reads the App Annie report. “Etermax claims that Trivia Crack saw 700,000 daily downloads in the US across all platforms.”

The studio now claims that Trivia Crack has 100 million players worldwide.

Crossy Road is another mobile game that had a big December. It finished last month as No. 3 on the most-downloaded list on iOS, and it continues to climb the grossing chart with an interesting payment model.

Like Trivia Crack, Crossy Road is something of an update. The game has you playing as a chicken (or dozens of other characters like Dracula) who must cross and endless field of roads, rivers, and train tracks. If that sounds familiar, it’s because it is a style of gaming that Publisher Namco invented back in the 1980s with Frogger.

Crossy Road has found an audience by updating that proven mechanic with stunning visuals and competitive elements that make you want to share the game with everyone. When you get a new high score, it puts down a marker that all of your friends can see as well.

The mobile release was already catching on with some audiences thanks to a strong buzz among game developers and critics, but Crossy Road blew up in popularity (and started shooting up the charts) when popular YouTube personality PewDiePie released a video of him playing it.

While it is free-to-play, Crossy Road doesn’t have bonuses or boosts that might taint the purity of its competitive core. Instead, developer Hipster Whale makes money through advertising and by selling in-game characters. That helped it get as high as No. 55 on the top grossing chart for all apps on iPhone in December.