Can you do 2D characters in 2.5D world with 3D lights?

Increator

I'd like to make something like Backbone or The Last Night -- pixel characters using low-poly normal-mapped geometry. Is this possible?

ChrisIceBox

Welcome to the community, @Increator.

In AC terminology, 2.5D refers to the use of pre-rendered image backgrounds and 3D characters. For something like the examples you mention, you'd be looking at 2D characters in a 3D scene.

AC supports the use of 2D characters in 3D scenes - you just need to rely on 3D Colliders instead of 2D Colliders for your sprite-based characters - but the lighting side of things is still handled by Unity and its render pipelines. AC wouldn't be involved with shading and materials.

If you instead wanted to use e.g. a simple quad mesh instead of a sprite, this would be a regular 3D character. To have the mesh face the camera at all times, you'd just need to move the mesh to a parent of the character's root object, so that you can attach a simple custom script that updates its rotation to face the camera in LateUpdate.

I'd recommend first testing your intended look without involving AC, instead using Unity's sprite system shader tools - including HDRP, if you want to have very realistic lighting.