Nice game, and interesting take on the theme!
The main feedback I have is that it would be good if the fire was a separate button from the other 2 interactions (say, fire is left-click, while water or village is right-click). I found myself getting frustrated at accidentally clicking trees when I meant to click tribe / water, which is especially easy to do when zoomed out more (which is also when accidental loss feels worse).
Being able to temporarily zoom back in on specific areas might also help with this (say using mouse wheel).
The other thing is that it wasn't clear to me at first the rules for making the water. I realized after that "downhill" in the description meant literally toward the bottom of the screen, but perhaps there would be a way to make this more clear in the game? (or at least say "downhill / toward bottom of the screen" in the description)