I think I mostly had difficulty aiming and moving at the same time.
I might just be a total noob to this type of game though, idk
If I were to make an easy mode for myself to play, I would probably just lower the health of the emenies, I think that's all I needed.
Also another idea is to maybe aim with the mouse
But it's your game though, so do your thing :)
Also I just want to say that this game looks amazing, and as a designer myself, I really appreciate it.