Kicking off the GDC Smartphone and Tablet Gaming Summit was a high powered panel talk entitled 'Guidelines for building cross-platform games'.

Including execs from some of the most popular free-to-play titles on iOS and Android, making the most of the current opportunities was key for everyone.

"We successfully took Crime City and Modern War from Facebook to iOS, and we're about to launch a title on Android too," explained Funzio's VP Jamil Moledina.

"Sometimes you have to be adaptive to see where the trends are taking you, as well as placing bets on emerging opportunities such as Google+."

Show me the money

"We're only on platforms that make money," explained Gamevil's VP Kyu Lee.

"We always start with C++ native development and we always try to have a simultaneous launch. Success on iOS will drive Android sales and vice versa."

For that reason, Gamevil hasn't released any games for Windows 7 because it's a C# environment. Lee hoped this would change with the release of Windows 8.

Through the opening window?

In contrast, Glu Mobile has been releasing game on Windows 7, and VP Mike DeLaet said that while it's a more complex business - especially in terms of coding - the company views it as a strategic opportunity.

"We look at every digital platform we can get our games on, and we think Windows 8 will be an opportunity in future, but you have to distinguish yourself with high quality content," he said.

"We see the industry as a three horse race between Android, iOS and Windows 8."

The other panellists were less keen on Microsoft's likely success, however.

"We look at which platforms have a vision that fit with our own roadmap?" explained Moledina. "But we also have to look at where the players are now and where we can monetise now."

"I wouldn't recommend Windows Phone at the moment, especially for free-to-play games," echoed Martin Chamrad, CEO of Craneballs Studios.

Opportunity value

Talking about the metrics of success, DeLaet said it was all about LifeTime Value of a user.

"We look at LTV per game. That's what everything is based around for us," he said. "It's extremely important in terms of user acquisition costs too."

Giving a different views of metrics, Gamevil's Lee said the company expects a game to make $2 million over its lifespan in order to consider developing a sequel.

He said the company is also looking to build out its global business

"There are a lot of hidden revenue opportunities. We've been slow in terms of localisation," he explained.

Indeed, pointing out an opportunity for western publishers, he said; "We've been making more than $2 million a month just from the carriers in Korea."