Tomba isn't 2D. It's 3D characters on a 2D line. A hybrid 2.5D if you will. Great games, but not quite a standard 2D game.
While on the not quite 2D games. Incredible Crisis. The game is 3D, but you really don't do much other than say, dodge left or right (while rolling down a street on a bike, or hospital gurney) or walk a flag pole.
Silent Bomber is a over the top (ala Gauntlet Legends) face paced game of awesome.