Progress made in Mass Effect 3 co-op multiplayer can be viewed on iOS devices, Facebook "and more".
You'll see a colour-coded map that will chart each area your squad has successfully defended, according to a deluge of information from OXM mined by StickSkills.
It sounds as though you'll visit these war-torn areas during the single-player campaign, and that multiplayer co-op enables you to take up arms and defend them.
The mined preview doesn't specify exactly how your multiplayer progress affects your single-player game. It does say that during single-player you earn War Assets - currency for purchasing allies, friendly fleets and facilities like radar stations. By exploring every inch of the single-player campaign you'll earn enough War Assets to be ready for the galactic war. This is the Galactic Readiness mentioned yesterday.
The mined preview doesn't explicitly mention earning War Assets during co-op multiplayer, but that's the suggestion. "The more you play and build up your multiplayer characters to survive increasingly tough odds," OXM wrote, "the more power and influence your single-player Shepard will wield by the time the endgame comes based on the amount of War Assets earned."
Mass Effect 3 co-op multiplayer will be wave-based, as was suspected in June this year. Each stage has eleven waves of enemies, ranging from basic Cerberus foot soldiers to Phantoms and Atlas mechs.
You earn experience points for kills, assists, objectives and other undisclosed actions. Downed allies can be revived but in a limited time-frame. Admiral Hackett orders the co-op multiplayer missions.
There's a level-cap of 20. Presumably Shepard can go higher during the main Mass Effect 3 game.
OXM added Drell (Thane) to the list of playable races. Soldier, Infiltrator, Engineer and Sentinel classes were mentioned. The final game will have more options as well as unlockables.
Krogan can charge and knock down foe; Soldiers can use the Omni-blade melee weapon.
Weapons and powers are selected before a mission. Weapons can be upgraded, as can armour.
Casey Hudson told OXM that multiplayer had been on the cards since the original Mass Effect, but ME3 was the first time he felt comfortable implementing it.
BioWare announced the Mass Effect 3 co-op multiplayer yesterday. BioWare is adamant that MP will be standalone and ignorable by those who prefer a pure single-player Mass Effect experience.