When you open Roald Dahl’s Twit or Miss (Penguin, 2015; iOS and Android), a British-accented voice welcomes you to “the ghastly world of The Twits.” Then you're ushered through an overgrown yard and into the Twits’ dining room, with art inspired by Quentin Blake’s classic illustrations. The app consists of a single game with a simple premise: Mr. Twit is eating dinner across the table from a sleeping Mrs. Twit, and he’s quite a messy eater. Players must keep the flying bits of chewed-up food from waking her up by flicking them away, either over her head or back toward Mr. Twit. If too many pieces of food hit Mrs. Twit, she wakes up and angrily whacks her husband with her cane, ending the game.

Play is intuitive; the “tutorial” simply reads “Don’t let anything hit Mrs. Twit! Complete missions for extra points.” On my first attempt at the game, I only scored 2000 points, but the second time around, I made it to 18000. The “missions” are simple tasks, such as lodging the food in Mr. Twit's beard, "plopping it" in his cup, or using it to squish the worms that periodically crawl across the table. Some food is sticky, some explodes, and the fish heads can be used as "spears" to poke Mr. Twit in the eye. The app — like the book it's based on — is a little disgusting and a lot of fun.

While the amount of flying food and the complexity of the missions increases with play, the app cycles through a fairly limited number of mission options. The sound effects of snoring, chewing, and mumbling also get a little repetitive, though I never failed to be amused by Mrs. Twit’s angry exclamations: “I’m going to whack you one in a minute!”

Roald Dahl’s Twit or Miss is not an educational app by any stretch of the imagination, and its appeal may wear thin after extended play. However, the overall experience is unapologetically gross and extremely satisfying. Points rack up quickly, the animated characters are reactive, and there is always a new mission to achieve. Plus, you get to fling around chewed-up food.

Available for iPhone, iPad, and iPod touch (requires iOS 7.0 or later) and Android devices (requires Android 2.3.3 and up); free. Recommended for primary and intermediate users.