At first it was unclear what was happening, and I assumed it was a kind of tower defense game. However, after I realised the units were targeting eachother not the trees, I found the concept very interesting. I quickly realised building up 4 trees and using mountains every turn to be a strategy that was perhaps too effective for most of the levels, but with further development and increase in level complexity I could see it being a real head-scratching puzzle game where you need to read the unit AI an plan moves effectively using a variety of the tools. Great job!