You play with your snail on a board filled with coloured marbles. You roll the dice, choose a starting point on the board and you pickup all marbles of the colour on the dice, as long as they are next to each other. If you meet a frog of an other colour then the dice, your turn is over. Same thing for your next turn, roll the dice, choose a starting point and collect as much marbles of the colour on the dice. First player to collect 10 marbles wins

From the designer:

In the late 80's, I was working as a consultant for UK Milton Bradley. They had a gadget that could pick up marbles which they liked but absolutely no game to make use of it. They wanted a game suitable for a 3 or 4 year old to play so I came up with this game. I think most children who were given Greedy Snail, played with the gadget as a toy rather than playing the game itself.