Religion & Jewish Life

Rabbi’s app sends users on a digital ‘treyf’ odyssey

The ancient laws of keeping kosher have now gone digital.

Rabbi Eli Garfinkel of Temple Beth El of Somerset, N.J., has gained a reputation as something of a technophile, creating videos and podcasts on Jewish rituals and a website called

Garfinkel recently found another high-tech outlet: developing smartphone “apps,” including his latest, “Treyf Invaders!”

Garfinkel described it as “a shoot-’em-up game that teaches players which animals are kosher according to Halacha (Jewish law) and which are not.”

Players must battle the evil “Hazirim Dominion,” which is attacking Earth by hurling animals at its population centers. The mission is to vaporize the treyf, or unkosher, animals and rescue the kosher species.

“I was trying to think of an entertaining way of teaching what makes an animal kosher or not without reading the relevant chapter of the Torah, which can put some people to sleep,” said Garfinkel. “This makes it much more engaging.”

Players learn that a lack of visible fins and scales make shellfish an enemy, birds of prey are generally off-limits, and desired animals must chew their cud and have cloven hooves.

Meanwhile, dreaded “bacon bombs” can result in an automatic loss of the game.

“People who like it the most are those ages 10 to 14, but really anybody can enjoy it,” said Garfinkel. “One of my friends in Texas let his son try it, and he thought it was a lot of fun.”

Treyf Invaders, available from the app store for iPhone, iPad, and iPod Touch through any carrier, is selling well for an unadvertised Jewish game, according to Garfinkel.

Two previous apps developed last year by the rabbi, Trope Tools and Trope Tools 2, designed to teach users how to chant Torah, have been purchased by hundreds of people all over the world.

Another of his applications, Reading Toy — which teaches youngsters how to spell simple English words — became available in June and is selling well, particularly in eastern Asia. Previously, Garfinkel came up with an application, Politicometer, which tests political allegiance.

“I’m now working on a basic Jewish quiz, things I think every Bar or Bat Mitzvah kid should know about the Torah,” he said. “Sometimes I fear kids don’t know their basics, like who is the first Jew. My students know that but I want to make sure other students are just as knowledgeable as my own.”

To get Treyf Invaders, go to