When there are three units in a row, the mouse-over text for the rightmost unit is off-screen and can't be read. There could also be better feedback for what the attacks are doing when they happen, especially for enemies; maybe have them move toward their targets for a split second and briefly show damage/healing numbers on top of the affected units. I also felt the game was too easy and kinda boring overall, so if you plan on expanding this into a full game, I suggest having more consistent challenges and get rid of luck-based mechanics like how your spider enemy can sometimes randomly decide to attack 0 units.