My current idea goes something like this: your mother has been dead for a year, of some unknown disease. For most of her time in the hospital, she would just play this virtual-reality-ish game (Quaternion). You had no idea why she would waste so much time on the game, and she would never say. She implied that she was working on something, but wouldn't say what.
Now, it's a year later, and you finally work up the courage to open the game yourself, not knowing what to expect. What you find is a giant structure built by your mother, with all kinds of machinery. It clearly has some purpose, but nothing is fully working at the moment. The goal of the game is to fix the machine and see what it was designed to do.
So I really, really like this story, from a story angle. It has that "discover your relative's old work" concept that's present elsewhere (Tron: Legacy, A Story About My Uncle, etc.), but adds a few twists to it. My only concern is whether it makes sense for a game like Quaternion to have an intro wherein someone starts talking about a painful disease killing their mother. Most of the game is going to just be "roll around this cool machine and solve puzzles and stuff," and although combining that kind of energy with a sentimental story certainly has been done before, it's a challenge to convincingly pull off.
Thoughts?