The guys at Extra Credits discuss mechanics as a metaphor or "mechanics with meaning" and for a visual aid, they use an interesting game or non-game called Loneliness. A description wouldn't really do the game justice, but it is well worth your time to try it for yourself considering the game is free.
One of the more interesting things brought up in this two-part series though is the lack of trust game creators show the player. Modern game creators simply do not trust the player to fail, experiment or uncover any meaning (assuming the creators intend for there to be any) while playing. After playing Loneliness you might understand why. It is a pretty gutsy thing to attempt in a free game, imagine how it would be received should you require payment for a similar experience.
Source: Extra Credits on Blip