Good Concept so Far, but the Response of the Game isnt really accurate.
I Never know which Character i actually have selected thats an Issue while SideScrolling.
Another Thing is that the Response of the Key Input feels like it takes 10 Seconds until something happen, thats not really fun. If i press a Key i wait for an instant Reaction.
Another thing is the complicated Keybinding with 1 Hand W and S for switching between the Characters while Movement is on A and D and Q is hit while E is Jump. Maybe overthink that for Example Character One on Alpha1 and Character Twow on Alpha2. The Movement at the Arrow Keys so you can use the other Hand for better interaction to the Game.
Maybe the Jump on Space and the Hit you can leave on Q or F. Just as Suggestion.
I think the Colliders from the Boulders are not really Accurate because sometimes you cant break any Boulder even you right next to it. Maybe they take more Hits? Then a Visual Indicator would be nice.
But a how i said the Concept is awesome but the Game needs maybe some Improvement.
Good Work
An Addition because i missed to shout out a bit the good Points: The Graphics are nice, also the Sprite Animation while Jumping and Hitting and when they together is really Nice. Sounds fits also very good for that Game.