I just beat this yesterday –NES version, of course –and while I enjoyed the early game, the difficulty spike in the second half is insane! I must have blown 50 lives on Level 7's space elevator alone, and Level 8's endless gauntlet of trail-and-error one-hit kills was really quite something.

Fun game with some good music, but it needed a complete difficulty rebalance. Apparently the GB sequel is better?