This was my favorite game of all time for many years, and it still is if I don't count RPGs. I poured 100s of hours into the NES game. I would beat a level, try the next level, die many times but get a little further each time, and then game over. I kept doing this until I memorized each level and they became easy(ier). I probably spent 10-30 levels per level doing this, and after enough repetition (and game overs) was able to memorize the entire game. The warps helped, as did the multi-1up trick on level 2. Later on I picked up a Nintendo Power which had all of the levels mapped out. I wish had that earlier.
I loved how every level in the game was completely different and required all new strategies. The Clinger Winger is probably my favorite. And the "3D" effects on the last level completely blew me away (sometimes literally, due to those damn blowing clouds).
Good times, I wish they would make another one but they would probably add save points and psuedo-unlimited lives like all new platformers do now. Kids now are a bunch of pansies and don't know what real difficulty is like
On the same topic, anyone remember the Battletoads cartoon and the arcade game?
Jam it back in, in the dark.