No idiots allowed
Ignore all the people saying "zomg the snake goes up down up up down down up whatever". Even if there IS a preset pattern, there's really no reason to memorize it. If the snake goes along the bottom with his mouth closed, he'll go along the top with his mouth open next time. Same goes with top closed, bottom open.
I only had two real issues with it. One of the worst things a game can have are permanently missable aspects unless they're INCREDIBLY easy to find or completely unnecessary. I don't really want to spend another hour playing this game again so I can get another 1000 points for a medal. Not this one, anyway.
Don't get me wrong it's not a bad game. I just have no reason to play it again unless I really want medals. All the enemies are in the same place, mushrooms, switches, etc. A sequel that includes more things to do and more ways to do it could easily be one of the best games on NG. As it stands, though, really the only thing it's got going for it is the great art and great programming. The gameplay needs work.