Focus on upgrades in this order:
This part is actually a little strange. You can go through the first
part of the tree like normal, but when you reach "More Upgrades",
Don't buy it until you can afford the upgrade after it!
Most other progression can be made via messing around. Note; it's
not always optimal to have as many levels of Exponential y as you
can afford.
Timewalls are almost nonexistent in Tree Game. Either