Can't hear the trees for the tuba

First version of the technology tree:

Second pass:

Greatly simplified third pass:

This last version feels to be of about the sight size and complexity for Colonial Zoo.

The first version above was drawn with KDissert, a neat enough mind-mapping tool. However for this use it has the problem that it can’t represent loops. The loops in the above image were made by stacking nodes. Bad.

The second two graphs were made with yED, a spiffy Java-based graph editor.