Here's some collated info, from interviews and such from various interviews and comments by Jordan Weisman and others at HBS, this is what we know so far:
Shadowrun Returns will be a single-player (for now) 2D isometric adventure game with tactical combat. We believe this to mean you'll explore, environment (Seattle of the 2050' in the Shadowrun universe) as you explore a branching story/plotline, talk to NPC's in a manner similar to the original SNES Shadowrun game with dialogue options and keywords, and then when you encounter combat a turn-based tactical movement system will engage, allowing you to strategize your teams combat actions.
You will build your own character from the following races: human, elf, dwarf, ork and troll - and the following roles - Street Samurai, Mage, Shaman, Rigger, Decker (and possibly Physical Adept, if we hit the final goal).
Some info on those roles:
"Street Samurai see a threat assessment overlay of the environment that notes enemy appraisals, options for cover, potential weapons, and statistics for drawn weapons."
"Combat Mages see magical auras, granting them the ability to locate magical items, identify spells being prepared, and find the intersections of magic lay lines where they can recharge their power."
"Hackers/Deckers see the digital control circuitry that allows them to manipulate the physical world via the digital one."
"Shaman see the “true world” that lies in the astral plane, distinguishing the true nature of people, plants, creatures, and magical objects while buildings and other “dead” objects appear as mere shadows."
You will also be able to hire NPC's to fill out your "team" for missions , and potentially hire your friends characters for missions as well, which if successful will get them some nuyen (in-game currency) the next time they check on their character. You won't be able to permanently kill your firends character, but if an NPC or friends character dies on a mission with you, you will not be able to hire them again in that playthrough.
Hope that helps a little.
Daniel.