"I want to create something that isn't already there, which is also appealing in a way," Erikoinen said in an interview in a shared, ground-floor conference room at Boomlagoon's new offices in a nondescript brick building in Helsinki. "Something that is instantly addictive -- as in "Angry Birds." But not the same thing as that."

What's so addictive about 'Angry Birds'?

That, of course, is easier said than done. In trying to create a new hit, the two men at Boomlagoon are leaning heavily on their experiences at Rovio, a company that made 51 relatively unsuccessful games and almost went bankrupt before coming up with "Angry Birds" in 2009. They know their success is far from assured, but they figure why not try.

"To be honest, I'd be happy if our game was just successful enough to keep our jobs and make a good salary," Erikoinen said, "but of course I aim for much more."

"Even if I'm shooting for the stars, 'Angry Birds' might be in a totally different galaxy," he added before disagreeing with himself: "But it might be as big as 'Angry Birds.'"

Here are five factors the pair hopes will make the yet-to-be-named game a success:

Focus on the characters:

One reason "Angry Birds" is a hit -- the apps have been downloaded a total of 1 billion times -- is that the characters are quirky and memorable, Erikoinen said.

Photos: Rovio's failed games

At one point in the creative process, the birds were more "goofy" than angry, but that changed because frustrated birds seemed more expected, he said. After settling on the birds' look, the game's developers -- there were 12 in all, including Erikoinen, who was the lead artist -- invented a story about the birds being mad at pigs that stole their eggs.