This app was mentioned in 7 comments, with an average of 1.14 upvotes
If I'm understanding correctly, this is your game--I checked it out on the Play Store and noticed Roll the Box. If this is the case, congratulations! It looks insanely, insanely hard but really fun.
I think the existing minimalist art style is a good fit for this game because it preserves visual clarity. The ground, spikes, and boxes all pop against the dark gray background. I also love the skins' minimalist character interpretations. If you're seeking to make the art style more distinct and textured, you might find inspiration in the dynamic lighting and subtle parallax of Thomas Was Alone, the bold monochromaticity of Solipskier, or even the pleasant abstractions of the Bauhaus movement. But I think you've got a good thing going already.