This is a curious one, a game where two snakes try to get as big as possible, eating coloured balls that do all that it's possible to flee from your tongue, and jumping around platforms filled with silly dangers.
That's it, you must eat coloured balls. Jumping, fleeing, getting rid of enemies and dying a lot is just secondary. If you want to get to the next level eat balls, because otherwise the weights that are on the far reaches of each level won't open the door.
But it's not as simple as it sounds. As, for starters, balls will get away. Not only bouncing but melting into the floor, using springs to jump further or growing legs to run aways faster than you. And their strategy changes from level to level.
Of course there are other nuisances. Like traps, plenty of them. From anvils falling on you to lives suddenly transforming into bombs when you get close to them. Or that shark, that funny fish that will hunt you down if you get into the water.
Well, that one is more a scheme to avoid you wandering away from the level, like is killing you if you fall for a few seconds, even if it was a small fall that would help you advance. Or even if it that descent is totally legitimate. You just have to go through the steps like a civilized person, or slowly go on the magic carpet or any other elevator thing.
But you won't care about it, because when playing this game what is left on your memory are the silly enemies, the funny and deadly traps and in general the lack of seriousness on the game, that can only compare to how fun it is.
This is what one expects from a NES game. Fun and for playing for a short time. And it even includes two players.