yeso well we made some resolution choices and stuck with them, which is part of it - but for the 2d and 3d meshing I think it comes from a few things:
1) we made rules for our 3d - no sharp edges textures, everything has to decay on the edges to appear somewhat organic. We learned this from looking at Black Matrix, a game that’s 2D but looks like they used a 3D reference, and the way they treated stairs and walls.
2) most effects are 3D instead of billboards, so an explosion will be a polygonal structure with transparent fire textures on it. Other effects are particles which is more like a layer on top of things.
3) 2D animations have certain frame limits (try to stick to 8 frames per animation at max) which helps keep them grounded and similar to each other, so internally consistent.
4) nothing can break the grid too hard, even when the grid isn’t visible. No hollow cylinders, gravestones can only be canted at certain angles, etc.
5) bosses follow similar texture limitations but blown up which keeps them in the world but also a bit different looking (since they’re meant to be a bit jarring)
6) we severely limit the number of colors in our ui and keep that language consistent and match resolution to our character avatars.
7) mixture of baked (2D) and real (3D) lighting makes everything feel lit and as though it’s in the same space. You’ll notice we light from the same side (southwest, with northeast spot lighting) almost always for this reason.
And of course we considered that this would primarily be played on HD screens when we put it all together.
I think that’s most of it! Hope that makes sense!