You can give your players incentive to do things, but if it’s not the incentive they’re looking for they will probably demonstrate it by their in game actions. Some examples of player incentives include:
Quakecon Keynote 2013 Annotated
An interesting but technically dense talk about gaming technology. I translate it for the non-coders.
Pixel City Dev Blog
An attempt to make a good looking cityscape with nothing but simple tricks and a few rectangles of light.
Video Compression Gone Wrong
How does image compression work, and why does it create those ugly spots all over some videos and not others?
Games and the Fear of Death
Why killing you might be the least scary thing a game can do.
Juvenile and Proud
Yes, this game is loud, crude, childish, and stupid. But it it knows what it wants to be and nails it. And that's admirable.