Well, you have to get to Mars anyway, so USE the yellow crystal again and click on the Great Face. You will be teleported into a chamber with three doors and, yes: more strange yellow markings! USE your yellow crayon to recreate the figure you saw in the map room inside the Sphinx, and all three doors will open. Go through the centre door, and you find yourself in the maze of coloured doors. TURN ON your lighter, go through the green door on the far left, and the yellow door on the far left of the second room; go all the way to the left, and you'll be in the Great Chamber. Zak can meet up with Melissa and Leslie at long last. No time for chitchat, though. Have Leslie put her helmet back on and WALK to the big pile of sand in front on the hostel. USE the broom alien on the sand, to reveal solar panels, then send her over to stand by the tram. Next, PUT ON Melissa's helmet, and send her over to the the tram. Finally, you have to send Zak outside, but he needs a spacesuit. PUT ON the wet suit, the oxygen tank and the fishbowl, then USE the duct tape on the fishbowl. Perfect! Send Zak to the shuttlebug where he can use the oxygen valve to freshen his tank and bring it up the full 15 minutes; then, send him to the monolith, and have him USE his CashCard in the slot. He needs only one token. Zak should then join the others by the tram. Save the game here!