Damn, I really like this idea. I can picture you going through receipts of like the one time he took you to lunch or a movie and memories being triggered. Or past due heating bills and you remembering a cold house in the winter. I think you are missing a sort central game mechanic, if you wanna go that route. Maybe the time thing can be it? Or it could be a Gone Home type of game where you focus really on building the dad's life through the objects not through any sort of mechanic. Not sure if that makes sense.