By Mark Ward
Technology Correspondent, BBC News website
Popcap's Bejeweled blazed a trail for casual games
For many years video games have been all about the hard core player.
These people, typically young men, have the time, budget and patience to spend hours crafting an empire or honing their skills on a first-person shooter.
But that focus is shifting dramatically thanks to a very simple game that involves creating rows of matching jewels.
When it first appeared in 2001 the game was known as Diamond Mine but is best known as Bejeweled.
Since then creator Popcap has sold more than 10 million copies of Bejeweled and the game has been downloaded more than 150 million times.
In technical terms Bejeweled is known as a casual game because it can be played for a few minutes rather than for the hours that games such as World of Warcraft demand.
James Gwertzman, director of business development at Popcap, said just because Bejeweled and its ilk can be played for a few minutes at a time doesn't mean they are without merit.
"There's nothing necessarily casual about playing them," he said. Popcap estimates that players rack up 600 million hours playing its online games every year.
The Wii has got many more playing video games
Importantly for the gaming industry the people raking up these hours are not traditional gamers.
"Popcap players are 65% female and 70% of them are over the age of 30," said Mr Gwertzman. "It's a demographic that's been completely and utterly written off as gamers."
The stellar growth of casual games is making that much less true than it used to be.
Figures gathered by the Casual Games Association suggest the industry is growing by 20% year on year and in 2007 the market for these titles was worth $2.25bn.
That growth is fuelled by the fact that almost anyone can play them, playing a level or screen takes a short amount of time, they are on consoles, PCs, phones and dedicated gaming gadgets and are either free or very cheap to buy.
By contrast games for the hard core take time to master, soak up huge amounts of time, are only on consoles or high-end PCs and are expensive.
Bejeweled blazed a trail but since then games such as Maple Story, Diner Dash, Jewel Quest and Mystery Case Files have expanded what can be defined as a casual game.
Perhaps the biggest casual gaming success has been Nintendo's Wii which in 2007 became the must-have console largely due to its appeal to the young and old who were never likely to spend time with a first-person shooter.
Amateur game makers can now find players for their creations
Toby Rowland, co-founder of casual game site King.com, believes social and technological forces have conspired to bring about the rising interest in casual titles.
The number of people who have grown up with games is increasing meaning there is an ever larger pool of potential players.
More importantly though, he said, were the advances in underlying technology that have made it easier than ever to get good games to people no matter if they are playing on a phone, console or low end PC.
"Broadband penetration is one of the big drivers on the industry and the other is the advance in the quality of Flash technology itself," he said.
According to Adobe more than 98.8% of the PCs being used in mature markets can run programs written in Flash.
Flash was important for more than just making titles look good, said Mr Rowland, it also helped designers make their creations easy to play but hard to master - one of the key qualities a game needs to maintain interest and keep people coming back.
Get the mechanics right and people will return time and again in an attempt to master a game. On King.com, said Mr Rowland, the average casual player stays for 40 minutes - a stickiness many other websites would envy.
The latest trend in casual gaming online follows some of the broader movements seen online. Increasing numbers of casual games allow players to take on others, compare scores and strategies and introduce a community element to the experience.
Others, based around sites such as Kongregate, allow amateur game makers to upload their own creation for others to try. The ubiquity of Flash and other easy to use coding tools has encouraged many to give it a try.
"They do not seem, on the surface, to be that hard to make, but it's a lot harder than most people think," warned Mr Gwertzman.
"There's no formula here," he said. "You cannot engineer fun."
That is something people have to discover for themselves.