2-4 is where I clicked away, as a singular datapoint for where the tutorialization/frustration/payoff curve is. I know I needed a double stack on the left and to do that I needed to push a block left from on top of the center blue, but the movement pattern wasn't immediately obvious. The slime's movement is the central mechanic, but I felt more like I was fighting it than vibing with it up prior to this point.