10 Incredible Singleplayer Features You Can Only Unlock By Playing Multiplayer
2. Increase Your Readiness Score By Playing Multiplayer - Mass Effect 3
The Mass Effect Trilogy has always only had one playable protagonist, the legendary Commander Shepard.
This said, Mass Effect 3 has introduced 4-player co-op multiplayer into the series, where the player can create their own custom character to participate in the galaxy-wide conflict with the Reapers.
In fact, if your character becomes really good at their job, they can even forge a legend for themselves in the single-player campaign!
Yes, although all the online matches happen with a custom crew and far away from where Shepard is, their outcome can directly impact the story in your regular playthrough.
Each successful co-op mission raises your single-player readiness stat in the Galaxy at War mode, which in turn impacts how well prepared Shepard's allies are for the final confrontation with the Reapers and what ending you're going to get.
Co-op mode is entirely optional, but participating in missions can greatly boost your readiness score, making the whole process of preparing for the finale less stressful.
And if your online character reaches a high enough rank, they can even be recruited in the Galaxy at War mode as a unique character!