Levels by Lobber
If Lobber is a less known D1/D2 level designer, then imo this is undeservedly so. I happened to stumble over his works just recently, and they have impressed me with their originality and their being refreshingly different. Lobber is the inventor of the 'bounce' levels, where many or all walls have an underlying force field making players and shots bounce off when touching them. He is also very fascinated with simple geometric shapes (pentahedrons and bodies with a hexogonal base) and by the ways you can assemble them to something far more complex. While this turns some of his levels into something that can be best marvelled at in a level editor, it makes others very impressive - just think of the fact that you can build a perfect (for the engine) sphere with pentahedrons ...
Click on the images for a visual impression.