Apart from the fact that it exists and that it has nothing to do with Shepard whatsoever, we really no nothing about Mass Effect 4. This – hopefully – may have changed today.
A Reddit user claims to have participated in a survey which revealed a ton of info about the next Mass Effect game. Take it with a grain of salt, but according to him, Mass Effect 4 takes place in the uncharted Helius Cluster in the Andromeda Galaxy whereas the original Mass Effect trilogy took place in the Milky Way. Apparently, the new game world will be 4 times larger than that of Mass Effect 3. And in that universe, the game's pathfinder protagonist will "encounter the remains of a once powerful and mysterious alien race."
Players will have to collect resources to improve their weapons and armor and they will be able to establish settlements on habitable planets and specialize them to produce more resources, or scout out more missions. Busy players will also be able to send AI-controlled mercenaries to fulfill less important tasks.
The game will see seven new crew members and will utilize a refined conversation capabilities allowing the player to interrupt conversations and to intimidate other with his gun. More importantly, the next Mass Effect will feature a multiplayer co-op horde mode.
Again, take all the above info with a grain of salt! Even if the Redditor's story is truthful, there is no real guarantee that the survey itself divulged real information. That said, the leak sure fits well with the Mass Effect universe.