Quoted from zucot:
Also, I'm in favor of letting you pick from any of the modes in the tree and not having a linear order every time.
This game just needs some tweaks and polish. Not a bunch of brand new stuff.
This would require a recalculation of scoring for "Stay Puft". Everyone would choose that mode as their first due to the insane amount of points it awards. Giving you the option, and Maybe not allowing the final mode in each ladder to be a choice is a great option.