I'm a bit curious, actually. I've experimented with a 2D tiling stuff in the past that used 3D hardware to render tiles, in 32-bit depth with simple (read gouraud) lighting effects and antialiased "sprites" (32-bit images moving over the top). I can easily imagine some retro style games doing that on modern hardware with pixel-shaded sprites and tiles for highly realistic lighting effects.
Where does that sit in the spectrum of 2D versus 3D ?
Have you ever try Hurrican ?
http://turrican.gamevoice.de/hurrican_site/To me, this is how 2D games should use modern graphics capabilities.
Regards,
Frederic