Though some levels can be ruthlessly-difficult, Earthworm Jim was a great 2D platformer on the Genesis and SNES with a lot of character, great visuals mapping hand-drawn cell animation to sprites, some funny slapstick humor that wouldn't feel out-of-place in a 90's cartoon (and sure enough there actually was a cartoon adaptation that ran a couple of seasons in the mid/late 90's), smooth controls, and solid level design.