Yesterday multiplayer support was confirmed for Mass Effect 3. Today BioWare followed up on that news by releasing a flood of details on the game's online play.
Mass Effect 3 will support four-player co-op in standalone missions. Players will create their own custom character, choosing a race and class, and join the fight to defend Earth from the Reapers. The multiplayer sports a character progression system with weapon upgrades and experience levels.
The most interesting part of the co-op is that it feeds into a larger system called Galaxy at War. In ME3's single-player campaign, Shepard is trying to gather allies, weapons, fleets, resources, and so forth for the final battle against the Reapers. The quality of the game's ending will depend on how high you've gotten the "Galactic Readiness" level through your efforts. Playing in co-op is one way outside the campaign to boost this Readiness.
"You can reach the highest levels of success in the single player experience alone, but Galaxy at War gives you alternative ways to get there. It’s about choice, and allowing players to find their own ways to stay immersed in the Mass Effect universe," said BioWare. In other words, you don't need to play the multiplayer, or use the Galaxy at War system in general, if you don't want to.
BioWare says that other "platforms and interfaces" for Galaxy at War will be announced at a later date. Each component of GaW will affect Galactic Readiness in a different way. The developers are trying hard to make sure that each component will "make sense for that platform."
My guess is that Galaxy at War will also be connected to mobile and social games. BioWare has dipped their feet in both pools with previous titles. They're both good candidates for secondary games that feed into Galaxy at War.