Video game stories come in a large variety of forms, from the barely existent story in Angry Birds, to the satirical barbs in Portal, all the way up through the multiple endings of Chrono Trigger. Mass Effect definitely falls in an unique spot on this continuum since the story itself isn’t very complex or deep. The universe is being threatened and one exceptional soldier fights to save it. But, unlike most other games, Mass Effect is laden with choices.
Because of the choices, if I had to compare Mass Effect to one other game, it’d be most like the living campaigns that take place in D&D and other roleplaying games. If you’re not familiar, the basic idea is that one central authority defines the setting and releases pre-written adventures, but it is up to each gaming group to make characters and play through the story. The adventures contain choices to present to the players, details about the NPCs involved, and even descriptive text to read aloud.
At the end of the day, dozens of separate groups could play the same adventure and have vastly different, yet similar experiences. Players from different groups could have discussions about the big bad evil guy; he probably had a deadly glowing sword in both of their games, even if in one he was described as having a green hat and, in the other, it was red.
Mass Effect plays like this. Bioware designed the setting, populated it with NPCs and set out the major plot points. But there’s enough branch points, decisions and customization options that each players’ experience is unique. Additionally, just like players in a living roleplaying game can take their characters from one adventure to another, Mass Effect let you import your character from one game to the next. If you saved a given NPC in the first game, they’d be in the second; if they didn’t make it, don’t expect to see them again.
This framework, which generated thousands or millions of different game experiences over six years, allowed the players to become uniquely attached to their characters, the NPCs, and the locations in the story.