Debug bodies shouldn't affect the physics at all, and in my testing they never did. Are you 100% sure this is whats happening?
crossy road is very possible, it's essentially 2D gameplay so you could get away without even using 3D physics. The rendering of course is also very easy to attain
that fracturing however is not easily attainable. You can kind of fake it but getting the real effect wouldn't be possible cause the physics only supports simple primitives or built up objects made of simple primitives (box,sphere,cyclinder).
I'm still too busy to work on Q3D atm.
You can fake cell shading somewhat, by having a larger shell mesh with reversed normals/backface rendering. The shading itself wont be cell but you'll get the "toon" outline, and could play with the specularity/ambient settings to obtain some kind of toonish look.