Here is a new update on my new engine (WIP!) on real hardware.
I didn't implement back the physics/controls, so don't pay attention to that.
What's new : compressed per-vertex animation with interpolation (a bit like Crash Bandicoot and Quake 2), VDP2 transparency fade in, per-vertex realtime lightning (on Sonic only), audio using tones, splitscreen (not seen here), octree instead of an uniform grid for culling/collision, paletted/CLUT sprites, LOD model autogenerated for distant quads and probably many other things I forgot to mention.
It's not optimized yet, so there is room for lot of improvement.