* Illustration: Apirat Infahsaeng * Eight years ago, Jason Kapalka and a couple of friends devised a puzzle game they called Bejeweled. It was simple: A grid covered with lo-res gems, which players swapped around to match up the colors. Yeah, it sounds stupid, but once you start playing, it's like crack.

Since its debut, Bejeweled addicts have frittered away around $300 million—and more than 6 billion hours—on the game and its sequel, the provocatively titled Bejeweled 2. And PopCap, the company behind the blockbusters, has become a big player—it now has more than 200 employees in offices around the world.

But Kapalka and his team still preach the gospel of simplicity. They spent four years and $1 million to try to make sure that PopCap's latest release, Bejeweled Twist, would be at least as intuitive and habit-forming as the original. We asked Kapalka for his take on some of the most addictive puzzlers ever made and why we can't quit playing them.

Solitaire

How it's played: Shuffle the deck, deal the cards into stacks, arrange them in order and by suit. Napoleon was supposedly a big fan—great for passing the time on Elba.

Kapalka's take: People compare Bejeweled to Tetris, but this is the real analog. Solitaire is a game in which skill isn't a factor. You're lucky or you aren't, and it just goes on and on until you're out of moves. Yet it doesn't feel completely random.

Rubik's Cube

How it's played: Twist the cube until the colors match on all sides. The toy, created by a Hungarian architect, set off a craze in the 1980s.

Kapalka's take: A clear example of a game in which the pleasure is in creating order. You randomize it, it becomes a big mess, and then you have to bring it to an organized state.

Where's Waldo?

How it's played: Spot the hidden object in a densely illustrated book. Turn page. Repeat.

Kapalka's take: There are paper variants going back to the 1800s that hide illustrations in the little curlicues of the margins. And there are new videogame versions like Mystery Case Files. For thousands of years, we've derived satisfaction from searching and uncovering—and we still do each time we turn up lost car keys.

Tetris

How it's played: As differently shaped tetraminoes fall from the sky, you pivot and position them to fill in gaps and form unbroken lines.

Kapalka's take: A timeless classic. Fitting pieces together feeds the same pleasure center of the brain that gets off on packing a suitcase really well or squeezing all your groceries into a single bag.

Collapse!

How it's played: In this PC title, colored blocks bubble up from the bottom of the screen. Mouse over groups of three or more and click to eliminate them.

Kapalka's take: You click wherever you want and something happens. It has that bubblewrap factor—pop, pop, pop. A completely mindless experience, but not in a negative sense—it's a letting go of conscious thought. Playing slot machines can be the same way.

Play Previous: Supersized Cruise Ship Is Longer, Larger, Plusher Next: Contest: Make Art From Starbuck's Junk Bejeweled Twist, Your New Digital Addiction

Mind Games: Play Videogames Just by Thinking Your Moves

Wired.com's Game|Life blog