Sam Sheridan plays Wordle the moment a new game drops, at midnight while he’s in bed, “which probably sounds kind of mad,” said the psychologist from London.

The game is simple. You have six chances to guess the day’s secret word, which has five letters. Type in a word as a guess, and the game tells you which letters are or aren’t in the word. The game is free and has no ads. The aim is to figure out the secret word with the fewest guesses.

Fans typically have a favorite first word they think gets them to the answer fastest. Two groups have emerged: those who type in vowel-heavy words first and those who go after common consonants.

Mr. Sheridan types in “arise” first, to eliminate three vowels at once. “I have not failed yet,” said the 30-year-old, who started playing a week ago. He likes to tease his girlfriend, Anna Taylor, who has no strategy at all. “I only find it fun if I can move instinctively and quickly,” said Ms. Taylor, 31, who works in clinical research. “His plotting frustrates me!”

Rebekka Power, 46, prefers more consonants in her first try and usually types in “stear.” She dismissed those who think a first guess should have more A’s, E’s, I’s, O’s or U’s.

“Words aren’t made of just vowels,” said the communications director from Melbourne, Australia.

Bertrand Fan, a software engineer in San Francisco, took a peek behind Wordle’s website to get a leg up.

He looked at the code used to build the site and found a list of words used in the game. But he didn’t use it to cheat. “It would ruin the game if I actually looked up the answer for each day,” he said. Instead, Mr. Fan used the list to find the most recurring letters in the words.

His analysis found that E, A, R, O, T, L, I and S were the most-used letters in the answers. He swapped out his previous favorite starting word “adieu” for “soare,” which means young hawk.

“I’ve never seen that word before,” said Mr. Fan, 41. He thinks it helps him win one try faster than “adieu.”

The game encourages people to share their results online, which helped it go viral. Jimmy Fallon, the host of “The Tonight Show,” tweeted his results to his 51.4 million followers last Tuesday. “Who else is playing #Wordle? Addicted,” he wrote. Three days later he posted an update. “Still hooked,” he said.

Players paste the Wordle game on social media, which has filled

Facebook

and

Twitter

timelines with a sea of green and yellow squares. In the game, when a guess is made, the color of tiles change to show you how close you are to the secret word. If you guess “weary,” as the instructions say, and the “W” turns green, the secret word starts with a W. If the E turns yellow, the letter is in the word, but is in the wrong spot. Letters that turn gray aren’t in the word.

Stefan Geens, 52, started playing last week after seeing the green and yellow tweets. He discussed with friends the best first word and settled on a few: “ratio,” “toner,” “tears” and “irate,” because they contained the most commonly used letters in the English language.

Then he realized he could do better. He spent a Friday night and a Saturday morning creating a Google spreadsheet to figure out the best first word. Using an online list of 2,499 five-letter words, it showed the most common occurring letters were E, S, A, R and O. He has now changed his first word to “arose.”

“That’s clearly the best guess,” said Mr. Geens, a product designer in Stockholm.

London-based Starling Bank Ltd. turned the game into an ad. “Britain’s Best Bank?” it tweeted. The names of rivals were wrong answers, while the word “Starling” was in green. Workers are fans of the game, said Oliver Mott, the bank’s head of social media. “We couldn’t resist doing a mock-up,” he said.

JJ Edmondson started a Facebook group last week as a place where people can post their results. About 170 people share their Wordle scores, as well as hints, clues and tricks. There is one important rule: “DO NOT REVEAL THE ANSWER!,” wrote Ms. Edmondson, 53, a teacher from the Australian town of Korumburra.

One trick she shares is how to get around Wordle’s once-a-day game limit. She suggests using the Wayback Machine, an online internet archive where people can see Wordle’s website from past days and play old games.

Ira Lilien, a retiree from New York, wishes there was a timer with the game to see if someone spent hours figuring out the word. When he plays, he types in words that contain S, T, E or R, letters he uses often in another word game, Scrabble.

Josh Wardle, the man who invented Wordle, is a software engineer from New York. He created a prototype in 2013 and during the pandemic he dusted it off for his partner, who liked playing word games.

It started to take off in mid-November, Mr. Wardle said, when technologist Andy Baio put a link to the game in his blog. Then Mr. Wardle noticed fans in New Zealand were posting results with color boxes they drew themselves. So Mr. Wardle made it easy to share results, and things went viral. He said 1.8 million people played last Friday, compared with 90 people on Nov. 1, 2021.

His email inbox has been filling up with people explaining their own strategies. He doesn’t know which one is best.

“You’re asking the wrong person,” he said. “I’m very bad at it.”

Corrections & Amplifications
Ninety people played Wordle on Nov. 1, 2021, the game’s inventor said. An earlier version of this article incorrectly said the year was 2020. (Corrected on Jan. 10.)