I am not sure if a 3D side scroller would limit the use of shaders and great light effects to show what can be done with Gamestudio.
While it would be possible to use postprocessing shaders to get a uniqe look or even use scanned watercolor textures to get a different mood compared to hightech glas/metal shiny environments - I think side scrollers are a bit "retro" and limit the player in a forward/backward trap.

EDIT
But leave this for later...

A great story can be implemented in different styles (side/iso/3D...)