Well.... I would do it with 2d sprites/graphics, but I would generate them via the 3d engine. That is say you know you need a wall "sprite" to represent a wall directly to the left, then I would put a camera and a 3dwall and would "screen grab" the wall. Then just paste that image whenever I wanted a wall like that to the left.
That is though only If I really really wanted it to be 2d, (like to run on old machines). If not I would just do it in 3d and be done with it.
That is though only If I really really wanted it to be 2d, (like to run on old machines). If not I would just do it in 3d and be done with it.