Bossa founders Henrique Olifiers and Imre Jele were involved in the development of RuneScape, a so-called massively multiplayer online game (MMOG) with more than 250 million user accounts set up since its launch in 2001.

Atomico, established by Skype co-founder Niklas Zennstrom, will have two seats on the Bossa board filled by co-founder and partner Mattias Ljungman and Atomico-affiliated games entrepreneur Alexis Bonte will join Bossa's board.

Worlds Adrift features pirates tasked with building an airship, recruiting crew and taking control of skies dotted with floating islands.

It is set to be the first game on general release to be built on the SpatialOS platform of Improbable, a British firm which in May raised $502 million in a funding round led by Japan's SoftBank Group Corp, valuing it at over $1 billion.

Improbable uses cloud-based computing to digitally simulate real-world locations for use in games and product design.

Bossa said the $10 million Series A investment will be joined by its original investor, London Venture Partners, which specialises in early-stage funding for new games.

It said it will use the funds to recruit staff to develop artificial intelligence, user-generated content and community-based gaming.

Massively multiplayer online games are likely to account for a large chunk of the $29.4 billion that market researcher NewZoo expects to be spent on PC games this year, out of $108.9 billion for the entire games market.

(Reporting by Eric Auchard; Editing by Christopher Cushing)