The Planet of the Vicious Creatures

"Portals... found buried on Earth. Who made them? We know not. Now we humble humans use them to travel to the stars." We have a new mission for you. Planet: Gliese 581 g. Tests indicate relative safety. Space suit will be required. Gravity 0.15g. You will find oxygen bubbles in the atmosphere. Beware of the fauna, stay alive and find a portal to come back for fame and glory! You can create new levels for the game or modify the existing ones and share with your friends.