Not holding back, so here goes :)
First off - way too many things happening way too fast. Your first order of business should be to work with the pacing and slowly introduce the player to the mechanics of the game, one by one and ideally explain how things work through a in game tutorial.
Second thing is readability in general is pretty bad. You have lots of units and options but it's really hard as a player to realize the difference between these units and why to use one over the other. Yes there is text there to explain but its hard to read it and especially when you have so much of it, you don't have time to figure out what all the UI elements are before you're dead.
Those are the two biggest issues.
My suggestion: scope down. A lot. try just having 1 or 2 units available, and 1 enemy type. Make them work really well. Create a proper UI where you can see, ideally with symbols or something that makes it obvious with a quick glance how much health, damage, cost etc. the unit has, the status of the game overall, where enemies are coming to attack etc. Work on introducing the player to how the game works slowly, give the player time to experiment and familiarize himself with the mechanics.
When you have a really strong, readable, playable and fun foundation, THEN you can think about adding more content. Now you have so much stuff in there, but the foundation isn't there - so it's all for nothing.
E.g. I had no idea about the whole monster points and summoning mechanics or even that I needed to get my units over to the other side. Yes you had a manual written down below the game but this isn't the 90s - noone reads that.