So many details to consider when you design a video game.

How high can the hero jump? What powers should the giant wasp have? What do you do when your pink spider refuses to die?

Such are the questions students contemplate this summer in new game design classes at Charlotte's Main Library and ImaginOn.

Since video games first became popular in the '70s, U.S. sales have reached $9.5 billion annually, and video games have become part of American childhood. Now, classes that teach kids to design their own games have begun popping up at summer camps and libraries across the country.

In Charlotte, the free workshops filled soon after they were announced.

Michael Camenga was among the first to sign up. He's been fascinated with how video games work since he played his first game at age 7. (For the record, it was Crash Bandicoot. “You run around and collect objects and jump over pits,” he explains.)

Michael, 17, wants a career in game design – a field with growing job opportunities. He's looking at UNC Charlotte's computer science program, which offers a certificate in game design and development. Central Piedmont Community College also has an associate's degree in applied science degree in simulation and game development.

In June, Michael took the library's first four-day game design workshop. After he breezed through it, Senior Library Assistant Mark Engelbrecht enlisted him as a workshop intern.

Classes, open to ages 8 to 18, are kept small – no more than six students per session. So far, most attendees have been male. Not surprisingly, they do everything at computers.

In last week's morning session, Jason Lage, 14, and Jose Cuellar, 12, begin by watching online tutorials and taking short quizzes through a Youth Digital Arts CyberSchool program. Within an hour, they're filling blank screens with green grass and blue sky – the background for their games.

From Pong to WoW

Video games first achieved widespread popularity in the early '70s with Atari's Pong, a game whose earliest graphics consisted of a circle bouncing back and forth across a screen. Today, everything's 3-D, and massively multi-player online games can support hundreds of players from around the globe.

Popular games – Dance Dance Revolution, Grand Theft Auto, World of Warcraft, Rock Band – rely on sophisticated programming and movie industry-sized budgets. But even simple game design requires critical thinking and cognitive reasoning skills, experts say.

In the library's workshop, students create two-dimensional side-scrolling games in which characters move across a screen. (Think Super Mario Bros., Sonic the Hedgehog.)

And they might not realize it, but when they're designing, they're creating narratives, using math, dabbling in physics.

“There's all of this logic. … It's basically what you do when you write a program for computer science,” says UNCC's Tiffany Barnes, an assistant professor of computer science and co-director of UNCC's Games+Learning Lab. “It allows the kids to be creative at the same time they're being really, really logical.”

Step-by-step progress

Jason and Jose drag and drop objects onto their screens – a house, trees, giant pink spiders, wasps, a Ninja, a little guy with a hatchet.

That's the easy part. To create a game, they give each object properties by making check marks on a grid: The Ninja can throw daggers and jump to a certain height. The wasp randomly changes direction each time it stops.

Then they program interactions: When a dagger hits a spider, it dies, and the dagger disappears.

Jason tests each step, asking a question when he encounters a hitch: “Whenever I hit a spider, it doesn't die.”

“Oh, you have to set it up to die,” Michael explains.

Little by little, the games grow more complex. By Thursday, Jason has finished one and has begun a second he's dubbed “Dragonball Z Escape,” which he's now adjusting after making it impossible to win.

Michael, who plans to write his Butler High senior exit project on how video games can be good for society, hopes the library offers more advanced software as students like him progress. “I'm always thinking up new things. When I play a real popular game, I think how I could change things.”

Jose puts the final touches on his game by making a dark, cobweb-laden “You Lose!” frame and a bright “You Win!” frame featuring a mermaid and a happy whale.

He studies the screen, pleased with his creation. He's gained a new respect for the folks who make games like Super Mario Bros. You take a lot of things for granted, he says, when you play a video game.