The last 5 puzzles of the game require some persistence to complete, but if you made it past The Statue, most of this should be a breeze. Here are the steps for completing puzzles 12-16 in Virtual Villagers 3: The Secret City.
Aromatherapy - puzzle 12 - You need to complete puzzle 8, have level 3 medicine, and a master doctor to complete this puzzle. Once you meet all three conditions, drop your master doctor on the completed bath. The doctor will fill the bowls around the bath with lotus plants. Once the lotus plants are in place, drop the doctor on the fire to light the burners around the bath and complete the puzzle.
The Door Key PuzzlesThree door keys, a white diamond, a pink diamond, and a pearl, are required to open the door at the top of the hill. The first to can be completed at almost any point in the game after you've completed the Alchemy Lab in Puzzle 3. The last one requires a bit more work.
The Ash Key (Diamond in Fire) puzzle 13 - After many hours of game play, a diamond will in appear in the fire pit. It's too hot for the villagers to touch, so you will have to cool it. Drag a villager to the waterfall and they will carry water to the firepit. You will have to keep dragging a villager to the waterfall to cool the diamond until it stops steaming. Once the diamond is cool, you can drag a villager to the diamond and they will carry it to the door at the top of the path.
The Hanging Key puzzle 14 - Up on the ledge above the roses is a pink diamond. To get it down you need to make a potion. The potion requires the combination Cactus + Rose + Lotus. Have a villager drink it then drag them near the rose plant. They should feel light and springy and will be able to retrieve the pink diamond and carry it to the door.
The Clam Key puzzle 15 - You must complete Puzzle 9 (The Statue) in order to get this key. A pearl becomes available when the statue is complete. Have a master builder pick up the pearl and take it to the waterfall to be finished. When the pearl is finished, have your tribal chief pick up the pearl to get the key from the Giant Clam. The key will then be placed in the door.
The Sun Dial puzzle 16 - To complete this puzzle, complete 13-15 first to open the door. This reveals the sun dial room. Place a villager on the sun dial room when it is at the far left position. When a beam of sunlight hits the sun dial ghostly figures appear. Drop a villager on the ghosts to reveal the mystery of the secret city.