Here's a sad song for some: Yesterday, the video game company Activision Blizzard announced that it would stop producing its once phenomenally popular Guitar Hero series to focus on its battle games such as Call of Duty. What slayed the rocking video game, once so central to pop culture that it inspired a "South Park" episode? Here are five contributing factors:

1. Sales were down
The game launched with a bang in 2005, raking in $1 billion in sales in its first 26 months. But since then, sales of the game have been slipping. "In a struggling economy, consumers weren't ready to drop the cash on the series," says Thorin Klosowski at Denver Westword.

2. The game cost everyone too much
The game wasn't just expensive for consumers, who had to purchase and store cumbersome instruments, it strained the company's budget, too, says Klosowski. Not only did Activision have to foot production bills, it had to license songs.

3. Innovation had reached a "standstill"
Some say Activision dipped into the "Guitar Hero well" too many times, and "I tend to agree with that," says Gieson Cacho in the San Jose Mercury News. Though the company produced many different versions of the game, Guitar Hero never seemed to evolve as much as its rival, Rock Band.

4. Plus, the market was over-saturated
Speaking of rivals, the market niche had become too crowded in recent years, says Chris Taylor at Mashable, as competitors like Rock Band, Warriors of Rock, Band Hero, and DJ Hero forced their way in.

5. It was, arguably, a flash in the pan
Maybe Guitar Hero was just a "passing fad like slap bracelets, pogs, and Hypercolor T-shirts," says Cacho.

But the beat goes on?
It's worth noting that "Activision isn't going to stop actually selling Guitar Hero titles any time soon," says Taylor. They just won't be producing new titles. You'll still be able to pick up the back catalog and work on "becoming a maestro of the pretend Gibson."