Shelved it after about 10 levels. If this were designed for a solo player, I'd give it a 2/5, but given that it's 27 years old and was intended for co-op play, I'm calling it a 3 instead. There has been plenty of evolution since this point, and it shows. Difficulty-wise, I'd put the levels I played between TNT & Plutonia, but much closer to TNT.