|I think about the 1600s or 1700s, there came a book called Pilgrim's Progress, by John Bunyan. It is a wonderful allegorical adventure story about the life of a Christian, told through the exploits of a man appropriately named Christian. He meets many thematically named characters that help (Hopeful, Interpreter, the Porter's daughters all have names like Charity...) or hinder (the Giant Despair, Mr. Worldly-Wiseman, Apollyon...) his progress from his home in the City of Destruction, along the Narrow Path to the Celestial City.
Just reading through the story smells like a rather straightforward adaptation to a Zelda-like action RPG (possibly FF-like RPG, but that might suit more his wife's tale). While something all riffed out with OpenGL would be neat, I'm thinking 2D would just as well suit the purpose.
The story itself does a great job of conveying the core of the Gospel truth, and if it were told through a video game to help it should be quite memorable. There are online versions of the text (it should be possible just to do a search on "download Pilgrim's Progress", I think that's what I did anyway!) for anyone interested in checking it out, whether for a game idea or for some high-quality reading.