Hey, all you sweet-toothed app developers: Cease and desist!

Newly armed with a provisional trademark on the word “candy” from the U.S. government, the British game maker behind the wildly popular app Candy Crush Saga has been going after mobile-gaming app developers using the off-limits noun, demanding they either lose it or close up shop.

Analysts and trademark experts were taken aback by the protection the U.S. Patent and Trademark Office had given King.com, whose highly addictive puzzle-game app has been a runaway hit with the mobile-gadget set. Tyler Ochoa, who teaches intellectual property at Santa Clara University School of Law, called the move “blatantly anticompetitive,” while others wondered whether other app makers would start seeking trademarks on a whole slew of everyday words.

“I was very surprised to get that warning because ‘candy’ is such a common word and I never dreamed anyone could get a trademark for it,” said Benny Hsu, a Jacksonville, Fla., game developer who found out this week in a form email from Apple (AAPL) that he and his app, “All Candy Casino Slots — Jewel Craze Connect: Big Blast Mania Land,” were in King’s doghouse.

After getting over his initial anger, and then deciding he didn’t want to spring for a lawyer to fight it, Hsu changed the free app’s name to “All Sweets Casino Slots.” But the taste left in his mouth was anything but sweet.

“My game looks nothing like Candy Crush,” said a befuddled Hsu. “My candies are rainbow-colored lollipops; Crush uses small green and red and yellow candies.”

King, whose highly addictive puzzle game has been downloaded more than 500 million times by Apple and Android users and was the most popular free app in the Apple App Store last year, has apparently asked only a handful of developers so far to remove their app, according to bloggers following the story. And its campaign seems targeted mainly against rivals with candy-themed gaming apps, not virtual confectioners like Candy Bar Maker or sugar-themed learning apps like Candy Count.

In a statement, a King representative said that because of a constant barrage of copycat developers trying to piggyback on Crush’s success by using “candy” in their names, “we have to enforce our rights and protect our players from confusion. We don’t enforce against all uses of ‘Candy’ — some are legitimate, and, of course, we would not ask app developers who use the term legitimately to stop doing so.”

Apple, which automatically sends emails to parties involved in a claim such as King’s, would not comment on the candy kerfuffle. And observers point out that Apple’s email to Hsu, for instance, doesn’t necessarily mean the Cupertino tech giant supports King’s effort to elbow away its rivals.

But the sweeping breadth of the trademark protection King received from the government, subject to a 30-day “opposition period” now underway, raises questions for Apple and anyone else involved in the burgeoning world of mobile apps. Hsu said that when he tried to create an app last year with the word “memory” in it, he “got an email from a developer that said ‘we own the trademark to the word “memory,” so you can’t use it.'”

Analyst Ben Bajarin with Creative Strategies said he was “surprised that King could get a trademark for a word so broadly used. They didn’t invent the word ‘candy,’ but they saw an opportunity to own it and fight their competition, which shows just how hard it is to have a successful brand and franchise in today’s era of mobile gaming.”

A patent office spokesman Tuesday afternoon said he was unfamiliar with the King claim and could not comment. But Ochoa at Santa Clara University called King’s candy trademark “unduly broad. I don’t think anyone identifies this app by the name ‘candy’ by itself. They’re attempting to get a monopoly or exclusive rights on anything that has the word ‘candy’ in it to prevent other people from making imitation games. That’s blatantly anti-competitive and it’s not what the trademark law is supposed to be about. It’s about protecting products and brands.”

Raising the specter of an all-out land rush by app developers using trademark protection to cordon off an endless string of everyday words, Bajarin wondered where it will all lead.

“For example, will people start seeking trademarks for titles with the word ‘football’ in them?” he said. “We’ve never really had to deal with this before in the world of software development, so everyone is learning as they go.”

Contact Patrick May at 408-920-5689; follow him at Twitter.com/patmaymerc.