King Digital Entertainment, maker of the wildly popular mobile game Candy Crush, went public this morning on the New York Stock Exchange after raising about $500 million in an IPO that valued the company at about $7.6 billion. But it fell short of that valuation with a poor early response from the market, with shares opening at $20.50 — beneath the offer price of $22.50 — and falling still lower to close down 15 percent by the end of day.

It's still a big win for the company's founders and employees, but the company has a tall order ahead. The number of people who play Candy Crush, along with the sales and revenue it generates, has already begun to slow down and taper off. If it's going to succeed as a public company, it will need to find a new source of momentum.

Zynga has made investors wary

The promise and peril of King's business is a common phenomenon in the gaming industry. Zynga, which built its fortunes around Facebook gaming and its infamous title, Farmville, has struggled to find another big hit and lost more than half its value since going public. Zynga tried to replicate lightning in a bottle by buying up other breakout games, spending around $200 million for the viral sensation Draw Something. But that title's momentum atop the charts faded quickly, and sequels never measured up.

King could easily have stayed private and milked this cash cow for many years to come. Its revenue in 2013 was $1.8 billion, of which a whopping $568 million was profit. So why go public at all? There are two simple reasons. King has raised $43 million from investors, and those backers typically demand the biggest return possible on their capital. Second, while yearly profits are nice, the founders stand to pocket a sum from this IPO that will launch them into the stratosphere of billionaires.

It seems investors have absorbed these concerns and are being more cautious with the King IPO than they were with its predecessor, Zynga. In terms of revenue, profit, and customer base, King is far larger than Zynga was at the time it went public. But King is opening at roughly two times the value of Zynga, a clear sign that the market is wary of being burned a second time. And with King's stock fluctuating beneath its offering price at opening, it seems investors have taken note.