One of the things that I thought about while reading what you wrote, is the fact that there are many non Christians who in the eyes of the world are very good people.
In other words, these kinds of people will probably make the right choice when given your example of the women who dropped the coin. However, this in no way makes the person any closer to God.
Your example only works in the case of people who are already saved. It that case, as indicated in the book of James, it shows the persons faith at work.

As I indicated in my other post, it might be a good idea if you can somehow use a catechism such as is found here in your game.
Why try to reinvent the wheel?

Tom