During a preview event at gamescom 2011, the studio showcased footage from the sequel and explained that the AI and co-op functionality have been improved as part of the overhaul.
Gearbox president Steve Gibson said: "We've been at this for a while. The team has gone through every system - weapons, vehicles, AI, quests, co-op, user interface - and either completely replaced or gutted every major system in Borderlands.
"This is a very, very ambitious sequel. This is not just a bunch of new levels."
The original Borderlands was released for Xbox 360, PS3 and PC in 2009. Four DLC expansion packs have since added to its framework, the most recent being 'Claptrap's New Robot Revolution'.
Borderlands 2 is slated for release in 2012.
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