I worked on my computer game, Crescendo, a bit this weekend after a long hiatus, and I made good progress:

I refactored the code that controlled the squirrel (the light blue circle) to use a state machine abstraction instead of the hard-coded way I had done the behavior, and I got the squirrel starting out with one acorn and planting it to grow a tree, which then gives out more acorns, and eventually filling the entire game field with trees.
 

 

 
The yellow square on the lower left is the Utopia terrain square with “The Root” planted on it–the heart of the Nature Kingdom in Crescendo. The Root is the green circle. The maroon squares are Ground terrain, and the green squares are Ground terrain have been fertilized by the squirrel to become Earth terrain, with the purplish circles in them being Oak Trees that the squirrel planted.