You are a snail in this story of saving your species, and you must make your way from entrance to exit in each of the 5 cave levels of the game. At the start of each level you drop into the cave from a hole, and you must find your way to the other hole that looks just like it. Problem is, it is initially closed, so you must first find the little switch that opens the exit hatch. Still with me?
(1) Find the switch, (2) trip the switch, (3) get to the exit.
Your only means of movement is by jumping, swimming or rolling. Using the mouse, point to the snail, then click and drag the mouse in the same direction you want to jump, swim or roll. The farther you drag the farther the snail will travel. Let go. Repeat.
Hint: if you hold the mouse button down for a couple of seconds, you will see the path of an arc drawn that the snail will take when you release the mouse button. This helps considerably when judging where and how far to drag the mouse.
Falling doesn't kill you, but enemies will. Fortunately, you are given infinite lives with which to complete the game. Also, at the end of every cave you will receive a password ('el código de la siguiente fase es...'). It will let you go directly to that cave in future sessions.
The enemies are nasty. There are white anemone-like things that will make you start the level over if you even touch them. And you will touch them, a lot. Yet persevere and be rewarded with a remarkable and wonderful Flash game experience.
Update: Due to a special collaboration with the author, an English translated version is now hosted here at JIG, and there is now one additional level to play, and boy is it a doozie! Says the author: "it's very hard, the hardest level you can imagine... and it has a new feature not present in previous levels. so enjoy."