Thank you for your detailed review and suggestions!
For the Life bar I'm not sure of what to do .. I don't want to make the take too much of the screen space and at the same time I know it's not ideal as it is. I'll follow your hints and see how it goes.
I'll do some tooltip for the Units / Stats for sure it's on my to-do list since the beginning I just have to find a way of keeping the Interface as simple as I can (I would like to ship the game on mobile without too much modifications) but yes it's needed ! I might incorporate all of that in the pause menu or directly in game what do you think ?
And lastly buying multiple Units at once it also a feature I fill missing. I have even the code ready for that as it was a bug I fixed not so long ago ^^.
Thank you again !