Video game maker Activision Blizzard Inc. said Wednesday that first-quarter earnings rose 19 percent, but it cautioned that the holiday season could be more difficult than it expected because of uncertainty about the global economy, new games and new consoles.

The company raised its full-year forecast for adjusted earnings to 82 cents per share from 80 cents per share. Analysts expected 85 cents per share.

The shares fell in after-hours trading.

First-quarter sales were helped by revenue from the "StarCraft II: Heart of the Swarm" PC game and the online multiplayer game "World of Warcraft," but the latter saw a drop of about 1.3 million subscribers, to 8.3 million.

"While we have had a solid start to the year, we now believe that the risks and uncertainties in the back half of 2013 are more challenging than our earlier view, especially in the holiday quarter," CEO Bobby Kotick said in a statement.

Kotick said he was concerned about shifting release dates for competitors' games, the "disappointing" launch of Sony's Wii U game system, uncertainties about other consoles, declines in "World of Warcraft" subscriptions, and the weak global economy.

The company said that first-quarter net income was $456 million, or 40 cents per share, compared with $384 million, or 33 cents per share, a year earlier. Excluding one-time items, the company said it would have earned 17 cents per share.

Analysts, who usually exclude items from their calculations, expected 11 cents per share, according to a survey by FactSet.

Revenue rose to $1.32 billion from $1.17 billion a year earlier.

Activision predicted second-quarter profit of 5 cents per share, in line with analysts' forecasts.

In regular trading before the results were announced, Activision shares rose 32 cents, or 2.1 percent, to close at $15.26. In after-hours trading, they were down 81 cents, or 5.3 percent, to $14.45.