Wordle. If you know, you know. For the uninitiated, Wordle is a very simple, brainteaser-style word game. You can only play once per day. Every player is trying to guess a word - the same word, for everyone. They're given six attempts. If one of your guesses has any of the correct letters, the game tells you.
It has certainly taken off online - every day hundreds of thousands of people head to the Wordle website to guess the word, to preserve their streak and compete with friends and family. The game was created by New York-based software engineer Josh Wardle, who joined RNZ to discuss his simple but viral game.
He says he created the game for his partner, as they are both avid fans of the New York Times daily crosswords.
"I wanted to create a game that she and I could play together, and that ended up being Wordle."
It has been going for about seven months.
A new game starts at midnight each day.
About 440,000 people worldwide are regular players.
"To be where it is now, it's a bit surreal."
On a per capita basis, New Zealand "is really into Wordle", he says.
"I should really do the maths because it's astounding."
In part it may be because of the country's small population so many of those on Twitter tend to follow each other so topics can go viral quickly.
While it's a solitary activity, it has also created its own community, for example, through the viral mechanic it has which allows users to share emojis that represent their grid. It is spoiler-free because everyone plays for the same word.
"You can't talk about the specific words that you guess because you'll give away the answer for people who haven't played. The emoji grid kind of removes all that content and just leaves the colours and it's a way for you to share how you did without ruining the game for others, which has really led to this communal aspect specifically on Twitter."
Wardle is quick to admit he did not come up with the emoji grid; a New Zealand woman (Elizabeth S) who was an early adopter began the trend.
"I'm meant to be sending you push notifications, I'm meant to be asking you for your email or your cellphone number, I'm meant to be allowing you to play endlessly.
"I'm kind of like 'what if I don't do any of those things, why does the internet have to be like it is, isn't that a bit disappointing?'."
At the same time he does not begrudge those who decide they do want to make money from their ideas.
The shared aspect, the decision not to have ads and not to have endless plays have added up to make Wordle a simple game that is also true to his own values, he says.
He describes it as a cross between Hangman and the board game Mastermind.
Once the player submits a five-letter guess word, the game will tell the user which letters are correct, which are in the wrong place and which ones aren't present in the solution word.
"So over the course of the game you have to use both logic and your vocabulary to figure out what word could possibly fit this pattern that is emerging."
Wardle says he came up with the idea partly because he played Mastermind a lot as a child. Mastermind has four coloured pegs that are hidden and the player is told how correct their solution is, although crucially the word aspect is missing.
"You know in Wordle that the answer must be a word in the English language and in Mastermind it can be any pattern. So there's no inherent information encoded into the solution."
He came up with the game in 2013 but a lukewarm response from friends led to him putting it on the backburner.
Wardle knows it is not an original concept and other word games are circulating, both online and on television.
He is not a software engineer and no longer has his former employer Reddit doing all the essential maintenance in the background, so managing the game is sometimes stressful.
He says it's a credit to his partner that Wordle players can be as competitive or as casual as they want to be.
While some want to "optimise it", some want to use it as relaxation, while others set themselves challenges.
"It could appeal to a bunch of different play styles and could kind of be multi-faceted in the way people engaged with it."
There are about 12,000 five-letter words and he and his partner have filtered the list down to about 2500, believing it's important to have words that have been reasonably common over the past 20 years.
Wardle, who now works for an art collective in Brooklyn, having trained in digital art, has also been involved in some community digital projects such as Place, while he was working for Reddit.
It was a massive-scale digital art project, using a blank canvas 1000 pixels wide by 1000 pixels high.
"We let you place a coloured tile, a pixel, anywhere on the canvas and you can draw things. Anyone can place anywhere, you can place over someone else's tile.
"There have been drawing apps on the internet before. The big difference with Place is that you can only place a tile every five minutes... so it immediately becomes apparent that you can't really do anything on your own... but what you can do is find a bunch of similarly minded people or convince people 'hey, we should go to this spot on the canvas and draw something'.
"That ran for three days and that just went absolutely bananas. People drew the Mona Lisa, like figured out how to collaborate and draw a representation of the Mona Lisa, thousands of separate individuals collaborating which was amazing."
He says while some might expect the worst to happen in such a situation, he believed that when challenged people would do the right thing.
"It was a bit of a leap of faith for us to do that ...fortunately the Reddit community didn't disappoint, they really came through."