From the cassette inlay:
The purpose of the game is to get home as quickly as possible from the depths of the Jungle.
To achieve this goal you must first cross the river using the stepping stones to avoid the crocodile, and then carry your axe to the forest.
Here you must chop down the trees, but watch out for the monkeys who will snatch your axe or may even kill you if you are defenseless. As you chop the trees your axe will become blunt and you will have to go back over the river to fetch a new one. When all the trees have been felled you must swing over the pit.
Beware, however, of the crevasse which appears at your feet. If you are quick you can leap for home and enter your time in the Jungle Trouble score table.