2d Top down game with camera pointing downwards?

I'm planning a 2d top down game, but I'm unsure to make it so that the sprites are all rotated 90 degrees, and the camera is facing downwards (down the y axis) so I can keep gravity as something which makes sprites fall away from the camera, or so I keep the usual x,y coordinates, and dump Unity's gravity and create my own?

 

If you want them to fall away from the camera, you're really no longer looking at using the 2D system. You're now in the 3D realm proper since Physics2D doesn't have the Z axis. Either fake it with 3D objects and textures, or fake it by turning off gravity and shrinking + layer sorting the sprites, along with your own gravity thing to calculate how much and how fast to shrink.

 

Thanks, yeah I think I'm going to have to keep it 2D and fake the gravity.