The hotkeys for actions are numbers 1-6 but I guess letters are more intuitive so probably I'll change it sometime. Good point.
To be able to use blocked whisp I consider adding 1x1 structures or ability to transport whisps over trees. I want to make the most of the blocking mechanics so I'll definitely keep an eye for that.
I agree the game requires some skill to play at current state. The obscure pathfinding with single selectable unit makes moving units require many inputs. There are some efficient tactics, you can abuse the fact that lumberjacks focus whisp more than oak and plane and lure them to the other side of the map. You can even abuse their pathfinding algorithm in some ways. I've managed to win Axetreme on large map but I had a lot practise. A tutorial or even pause menu would be good to learn basics.
I didn't have time to implement everything. There are still things like fog of war and minimap that are mandatory for a proper RTS. In fact there are much more things on the list for this project including rewriting everything at some point. If I continue working on this I'll add some things to current version first because they are crucial to understand before spending time to plan everything from scratch.