Tombs & Treasure/Beneath the Well of Sacrifice

The Ball Court
Several screens west of the Temple of Warriors, you'll find the entrance to the ball court. It's unassuming, but it can be found around the set of steps near the northern portion of the grassy field.
 * LOOK at anything: A Hornskull will appear
 * FIGHT the Hornskull: Provided you are above Level 15, and have joined the Blue Jewel with the Sword, you should be able to defeat the Hornskull.
 * LOOK at the Cog: You will notice that it's being held in place by a pawl.
 * GO ⇑
 * LOOK at the Blue Block: Your instinct might be to try and smash it, but that won't work. However, you can actually take the block.
 * TAKE the Blue Block: An entrance will appear on the right. You can go through it if you want, but don't do anything in the room beyond.  Instead, exit the court.
 * GO ⇓
 * GO ⇓

Return to the High Priest Tomb
Head south a few screens to return to the High Priests Tomb.
 * GO ⇒
 * LOOK at the Skeleton
 * MOVE the Skull: You will find a keyhole behind the skull.
 * USE the Iron Key: The lid will close and the coffin moves away to reveal a hole that leads to a corridor.
 * GO downstairs: You will arrive in the underground corridor that is actually below the Ball Court. The entrance will close behind you when you enter.
 * GO anywhere: No matter where you go, it all looks the same. Eventually, the girl will suggest that you make a compass.
 * JOIN the Small Rod and the Shallow Bowl: This will make a compass and allow you to find your way through the corridors.
 * USE the Shallow Bowl: You follow the compass until you reach a small room with a stand in the middle that holds a small jewel. You should also notice two exits from this room.  You came through the right door, but the left door was created when you took the blue block.  If you do not see two exits, then you will be stuck here forever, unable to complete the game.
 * LOOK at the Akbal Jewel: It is said that this jewel has the ability to rob demons of their power.
 * TAKE the Akbal Jewel: The door that you just came through, the right door, will slam shut, but the left door should remain open.
 * GO ⇐: From here, if you go forward, you will find that it's too dark to continue. Furthermore, if you examine the wall, Jose will explain that you might be able to see something if you had a mask.  However, no combination of the One-eyed Mask with either jewel will produce any results, so he must be referring to a different mask.
 * GO ⇓
 * TAKE the Stone Pawl: This will cause the path to the corridor beyond to close behind you. Attempting to replace the pawl will have no effect.  However, you need this pawl to continue, so take it with you.
 * GO ⇓

The next step
At this point, it isn't entirely clear where you should visit next. However, having obtained the Blue Block, there is a location where you might be able to place this block. Return to El Castillo.
 * PUT the Blue Block: Doing so will cause an entrance to appear in the floor.
 * GO downstairs: You will arrive in a room with a mechanism on the wall. The mechanism is made of many cogs.  If you allow Jose to try and move the Stone Handle, it will move, but then return as soon as you let it go.
 * LOOK at the Shaft: It looks as if something was once attached there.
 * PUT the Stone Pawl: The Pawl will attach to the shaft.
 * CHANGE to Jose
 * MOVE the Stone Handle: You will hear a loud roar. The girl will remark that it sounds like water flowing.
 * GO upstairs
 * GO ⇓

The Well of Sacrifice
There are two bodies of water in the game. You have visited the Well of Paradise, but now it's time to check the Well of Sacrifice, to the east of the Temple of Warriors. If you visited it earlier, you have seen the well full of water. But now when you visit, it is empty.
 * GO downstairs: Before you enter, Jose warns you that people who entered the well were trapped by a Crystal Prison and light, and tells you to make sure you have the Crystal Key and a mirror. To fight the demons, you'll need the blue jewel and the Akbal jewel.  You should have all of these items.
 * GO downstairs: Jose will suggest that the girl should wait behind. But the girl does not want to be alone, so Jose stays with her, sending you in alone.
 * LOOK at anything: A "Venom" will appear.
 * USE the Akbal Jewel: After you chant over the jewel, the Venom will be more susceptible to your attacks.
 * FIGHT the Venom: Provided you use the Akbal jewel, and combine the blue jewel with the sword, you should be able to defeat the Venom.
 * MOVE the right Head: The door will open.
 * GO ⇑: The door will close behind you. The room you enter contains a coffin and a beam of light coming down from the ceiling.
 * USE the Golden Mirror: The mirror will reflect the light on to the pattern on the wall, and cause an exit to appear. If you do not do this first, you will become trapped in the room.
 * LOOK at the Coffin: You will discover that the coffin is hollow, and you can see a body wearing a mask inside. The coffin has a hole on the side.
 * USE the Crystal Key: The key will open the coffin.
 * TAKE the Two-eyed Mask
 * GO ⇓: The light is gone, rendering any chance of escape hopeless if you did not already use the mirror.
 * GO ⇑: You will now find yourself back in the room below the treasure room of El Castillo.
 * GO upstairs
 * GO ⇓
 * GO ⇓

Return to the Well
When you arrive, you will find Jose lying unconscious on the ground, and the girl will be nowhere in sight.
 * LOOK at Jose: He will wake up.
 * LOOK at Jose: Jose will explain that some group kidnapped the girl, and that they took her to their lair, somewhere in Ball Court.
 * GO ⇓

Getting back into Ball Court
When you left Ball Court, you took the Stone Pawl which was keeping the entrance to the corridor open. With the pawl gone, the entrance is shut. However, there is still another way to enter the court. If you remember, you had to travel through the High Priest Tomb in order to reach the passages below Ball Court. Return to the tomb now and retrace your steps.
 * GO ⇒
 * GO downstairs
 * USE the Shallow Bowl: You will return to the room where you obtained the Akbal Jewel.
 * GO ⇐
 * GO ⇑
 * LOOK at the Wall: Jose will suggest that you might be able to see something if you use a mask. However, just using either mask alone reveals nothing.
 * JOIN the Red Jewel and the Two-eyed Mask
 * JOIN the Blue Jewel and the Two-eyed Mask
 * USE the Two-eyed Mask: You will notice a white block along the left wall.
 * PUSH the White Block: You will create an entrance on the left.
 * GO ⇐: You will enter a new room.
 * LOOK at anything: A "Tezcat" will appear.
 * JOIN the Blue Jewel and the Sword: You must reset this connection in order to damage the Tezcat.
 * FIGHT the Tezcat
 * LOOK at the Temple: You will see a golden key inside, but you need to open the model temple to get it.
 * WAIT until midnight: If you recall, one of the tablets in El Castillo mentioned drinking a potion at night to become smaller. Wait until the circle at the top of the screen turns black.
 * USE the Large Flask: Jose will turn into a demon Scareface and demand the flask! He will explain that it was his friends who kidnapped the girl, and that all he needs is the Sun Key in order to rule the world.  He plans to defeat Tentacula himself, and kill you too.
 * USE the Akbal Jewel: You'll need to do this in order to harm Scareface.
 * FIGHT Scareface: Even if you've done everything right, this fight can be a close call. Leave the room and come back to try again if you get too close to dying.  You will retrieve the Ring of Itza upon defeating him.
 * USE the Large Flask: This time, you will shrink down to the size of the temple.
 * GO ⇑: You will enter the temple. There is a keyhole on the left.
 * USE the Silver Key: The whole temple will shake. It is now unlocked.
 * GO ⇓
 * USE the Small Flask: You will return to your normal size.
 * MOVE the Temple: Unfortunately, even after using the Silver Key, the Sun Key is still not quite accessible from the Temple. You have to move it first in order to open the doors.
 * TAKE the Sun Key: The scene will immediately change, the room will shake, and you will find yourself in the Shrine of Tentacula.

The Shrine of Tentacula
It looks like you found the girl, who is lying on the stand in the back.
 * LOOK at anything: Tentacula will appear before you.
 * USE the Akbal Jewel: As usual, you need this to harm Tentacula.
 * USE the Itza Ring: This is also necessary to protect you from harm.
 * FIGHT Tentacula: This fight will go on for a considerable amount of time, primarily due to the frequent dodging of attacks on both of your parts.
 * LOOK at the Stand: You will find the girl lying down.
 * LOOK at her Face: You will notice that she's not dead, but merely in a deep sleep. You'll need to use the Censer to wake her.
 * GO ⇓
 * PUT the Censer: You will place the Censer on the floor.
 * PUT the Incense: You will place the Incense in the Censer.
 * USE the Lighter: You will light the Incense and it will give off a pleasant smell. It will wake the girl from her sleep.  After you catch her up on the details, she will instruct you to use the Sun Key.
 * USE the Sun Key: The shrine will begin to collapse, and the ending to the game will begin. Congratulations.