It’s a question that lingers on the minds of many a game developer — how long does it take for a free-to-play game to make a profit Well, the answer may not be simple, but a new report from eMarketer has provided some valuable insight.

A report turned in last month by deltaDNA took an overall look at usage data for more than 1,000 mobile games with 100 million players worldwide. Out of these findings, strategy and action free-to-play games seem to have the strongest retention rates, at 30 and 29 percent, respectively.

They didn’t stay there, however, as both numbers dropped after seven days into the report, while social casino games moved to the top, with a retention rate of 15 percent, followed by puzzles (11 percent). deltaDNA made it known that these games have better retention, mainly due to long-term playability. The chart below breaks this down a little more significantly, including dollar values based on these percentages.

Retention isn’t the only statistic to pay attention to, however. Average revenues also play a big part, with strategy and action games getting $1.80 and $1.40, respectively. Strategy games are more likely to see spenders convert for the long haul, mainly due to the “time blocking” system, where users have to wait to refill hearts or resources if they don’t wish to pay up front for them.

That said, puzzle and social casino gamers still play a big part. With a shorter window where players likely spend money, they have a slightly smaller value, although both types of these games have a long-term approach when it comes to monetization, across low-value transactions. That makes them just as profitable in the long run, compared to big purchases in strategy and action games.

As far as the number of monthly in-app purchases made by mobile gamers, the chart (taken from data early in the year) shows that most are pleased with one in-app purchase on a freemium release during the month. However, there’s a pretty healthy amount making multiple purchases, with 20.3 percent clocking in with five or more.

Mobile gaming is big business, as eMarketer estimates that there will be nearly 165 million mobile phone gamers in the US this year, which makes up more than half of the population. 113 million of those consumers will play these games on tablets. In addition, US mobile game revenue is expected to skyrocket an additional 16.5 percent this year, reaching a whopping $3.04 billion. That makes up nearly 31 percent of overall mobile download and in-app revenues.

These are sure to be music to the ears of free-to-play game developers. But remember, big and small spending both play a part, as this report indicates.