Assuming everything you're using is a sprite (no polygons), have you considered using anti-aliasing (AA)? The pipes especially look bad without AA.
Godot can't do AA on polygons yet, but for sprites it should be fine.
Yeah, we kinda had to embrace the terrible graphics to get it done in time. Among our other sins are rotating and arbitrarily rescaling pixel art. We're working on the sequel right now, we'll be taking more care over the graphics although the gratuitously large (4x4) pixels are here to stay. If you're interested in alpha testing hit me up on the TairaGames discord sometime.
I am talking about the rotation or your art, not the art itself. Particularly I mean AA in the project settings of Godot, so your rotated pixel art looks better. Making 1:1 pixel art is more of a style issue.
I wouldn't mind testing, although I don't use Discord (I prefer IRC).