CHAMO

For my recent gm48 entry I made some trees with physics-like attributes using procedural generation and recursion. The player controls a chameleon (which uses circle intersections for IK joints and it figures out where to place the feet). The chameleon follows the mouse cursor and can move between trees and branches. The theme for the gm48 was "color is important" so my implementation was to make the flies essentially fly away from the player if they're not matching the leaf color (using the mouse wheel to control hue) otherwise they're easy pickings. You can grab the source over on yoyogames marketplace if you're more interested in how it works: https://marketplace.yoyogames.com/assets/7919/procgen-trees 

If you do grab the source and have questions on something (it's not heavily documented because it was made within 48 hours) let me know.