Thank you so much for trying out our game, I really appreciate you taking the time and that is some gold play-testing feedback & suggestion for features! (We took notes).
Some of the points you point out are really on the spot, purifying the corruption is a game design feature that has been sidelined for now.
We intend for the player to eventually being able to collect a magical resource that are produced by the healthy trees which in turn can be used to either heal the damaged forest areas or to make the character's ability stronger.
The reason why you lose the game right now is because too many sections of tree's dies, this number is currently set to two which is way too low. (And we got this feature in the same day that we built this version so it does not have any kind of feedback to tell you what is happening), sorry about that hah.
We are intending to make the game space shrink when you lose to many sections of forest sort of like you see in a battle royal, with poisonous smoke dealing damage over time to the player if they stay in it. This is to gradually make the game feel more and more intense as it progresses.
Again, thank you so much for trying out our game I was really humbled to watch the video, means a lot to us. Really hope you try our game out again in a couple of months when things should be working more as intended and with more features added. <3
Ps: You totally messed up our last names, but all is forgiven.