Non-destructive

Complete the game while obeying the following rules:


 * You cannot cause the destruction of any tree with the exception of the horizontal "dead" trees. You cannot destroy normal trees that have lost all their leaves due to pollution. If biters destroy trees this does not count.
 * Do not use landfill.
 * Do not use cliff explosives.

You are allowed to mine rocks but you can avoid doing this if you want to increase the challenge further.