Blizzard has been silent on Blizzard All-Stars, its MOBA first revealed at BlizzCon 2010, for months now.

Fans had hoped for an update on the team-based competitive spin-off late last year, but Blizzard has only mentioned it in passing in interviews and financial calls.

The official Blizzard All-Stars website doesn't help much either. It reads: "coming soonish."

Last week StarCraft 2 production director Chris Sigaty told Eurogamer Blizzard is "actively working" on the game. So what's the hold up?

Sigaty said Blizzard is working on the systems required to deliver a business model it has yet to dip its toe into: free-to-play supported by micro-transactions.

"We're actively working on it," he said. "That I can confirm. A lot of the stuff that's remaining right now that we need to focus on are the systems necessary to pull off a game with a different business model than StarCraft 2.

"StarCraft 2 is a box. We intend to do something different with the business model in Blizzard All-Stars, something more closely resembling the other types of games in that genre, the MOBA-style games that are out there today, and being able to sell smaller amounts of things to players, the things they want."

The leading MOBA light is Riot Games' League of Legends, which enjoys astonishing popularity with a free-to-play business model that allows players to spend real world cash on champions from an an ever-growing list. Valve, too, is enjoying great success with Dota 2, not yet out of beta but with some three million players a month.

Blizzard All-Stars looks set to offer a similar way of paying and playing to those games, incorporating heroes from across the impressive Blizzard universe, which encompasses Warcraft, StarCraft and Diablo.

"Those systems are what we're working on right now," Sigaty added. "But yeah, it's still actively being worked on."

Blizzard All-Stars was called Blizzard DOTA before Valve put its foot down with the DOTA trademark. As part of the settlement between the two companies Valve was allowed to use the DOTA name in a commercial setting, while Blizzard retained non-commercial use of the title for its community, with particular regard to player-created maps for Warcraft 3 and StarCraft 2. But, crucially, Blizzard agreed to rename Blizzard DOTA to Blizzard All-Stars.

It was also one of four internally-developed mods for StarCraft 2 and intended for release on or near expansion Heart of the Swarm. Now, it seems certain to be a standalone game. Sigaty refused to go into detail (rumour is Blizzard will re-reveal Blizzard All-Stars at BlizzCon later this year), but did offer this:

"We'll go into more details about that in the future but I suspect you will not have to have StarCraft 2 to play [Blizzard All-Stars]. We're definitely emphasising it as its own product in the future."

No release window has been set.

In August 2011 Blizzard told Eurogamer it had completely rebooted Blizzard All-Stars. The version shown at BlizzCon 2010 had been "flattened", the company said.

At the time executive vice president of product development and Blizzard co-founder Frank Pearce explained that Blizzard hoped to make Blizzard All-Stars more accessible to newcomers.

"One of the important things to note with that space is the DOTA everyone plays on Warcraft 3 is not particularly accessible to the novice," he said. "One of the game development philosophies we have at Blizzard is, easy to learn and difficult to master. That mod for Warcraft 3 doesn't really fit that description.

"That's a big challenge for us: taking this concept that doesn't really fit that philosophy and adapting it to a philosophy that's important for us."