Although it claims it's already profitable, US tech outfit Sibblingz has taken around a second funding round from its incubator parent YouWeb to speed delivery of its cross-platform Spaceport game engine.

YouWeb seed funded the company with $500,000 in May 2008, and has added a further $1 million. Sibblingz says it's generating 'millions of dollars a year in revenue share fees from games using its technology'.

Facebook face off

The cash will be used to get Spaceport compatible with Facebook's Project Spartan. It already offers developers the ability to create HTML5 web games and native standalone games for iOS and Android from a single Javascript project.

"We have been working with multiple Facebook game developers who are preparing for the rumored Project Spartan," said Ben Savage, Sibblingz founder.

"They all want to be the Zynga of mobile gaming. We are happy to help them challenge Zynga".

"YouWeb rarely leads financing beyond the seed round but we felt that Sibblingz is a unique disruptive play in mobile gaming that involves the trifecta of Zynga, Apple and Facebook," said Peter Relan, founder of YouWeb.

"We simply could not pass up this opportunity."

You can find out more from the company's website or check out the following video.