Brothers in Arms: Furious Four is a sort of Inglorious Basterds styled sequel to the po-faced and mostly authentic Brothers in Arms games, which is a bit like having a Police Academy film set in The Wire's universe. Perhaps realising this, Gearbox has severed Furious Four's ties with the more solemn Brothers in Arms franchise, allowing it to go full-on wacky without upsetting fans of the original games, which were based on the lives of real soldiers with actual families. Furious Four is now its own strange, co-op World War 2 thing. Everything about this decision makes sense.
The decision to turn Furious Four into its own property was revealed by Gearbox at their PAX Prime panel, with Gearbox boss Randy Pitchford stating that “our Pokémon has evolved. It has different powers.” Having worked on a Nintendo magazine for two years, I can tell you that's a poorly utilised metaphor. Pokémon have moves, not powers, but that at least explains where the game's been since its announcement at E3 in 2011.
Details are scarce as to what, exactly, Furious Four might become now that it's been unshackled, though Pitchford suggests that the the newfound freedom will allow the team to introduce better ideas, drawing a comparison with the genre-blending Borderlands franchise. Furious Four was originally slated for a 2012 release, though this "evolution" will no doubt punt it right out of this year's release schedule.
Ubisoft allowed the Brother in Arms trademark expire earlier in the year, though Gearbox say the franchise will return in some form, teasing further information to be revealed at their community day on September 15.
Here's the game being revealed at E3 in 2011.