With all the buzz about Flappy Birds and the IPO filing by Candy Crush Saga maker King, it's clear that the mobile gaming market continues to be white-hot. But according to a study released this week, getting people to pay for games is actually a major struggle for developers.

The report from app-testing company Swrve found that a mere 1.5 percent of players spend any money at all on mobile games and that 50 percent of all in-app purchases on free-to-play games came from 0.15 percent of players.

The data suggests that mobile game makers are extremely reliant on players the gaming industry refers to as "whales"--those who spend huge amounts of money on in-app purchases while enjoying free-to-play games. Outside of these select few players, many game makers are having a hard time monetizing games, a potential business model flaw.

In other mobile gaming news this week, a district court dismissed a lawsuit filed against Zynga by shareholders who claimed the game maker misled them about its financial state prior to going public.