Top iOS developers are using a tried and true tactic in revitalizing their best-performing titles with special holiday editions.

This week, Finnish developer Rovio and San Francisco Bay Area-based TeamLava, have seen Valentine’s Day versions of their bestsellers reach the highest-grossing charts, with Bakery Story sitting at 37 in the U.S. and Restaurant Story at 47. Angry Birds Seasons is fourth among all paid apps.

TeamLava, which is one of the leading mobile developers to use virtual currency, offers a very basic holiday-themed skin of its game Bakery Story with new pastries and challenges. Its top in-app purchases still involve the in-game currency Gems, which sell in bundles that cost up to $99.99, although the most popular price point is $4.99. The company’s other Valentine’s Day app Restaurant Story also adds special quests.

Because Rovio has so far focused on paid apps and advertising, its special Seasons app doesn’t have any virtual goods or in-app purchases. Instead the company has added 15 new levels and romantically-themed challenges, that put pigs in hearts made of glass and other whimsical designs that the birds have to knock down.