Grimrock

In the pyramid of the great dragon, the door that supposedly opens by putting Toorum's remains in the alcove, I opened it without putting Toorum's remains, by pressing some of the buttons on the level (I don't know which one exactly).

In the outdoor ice level there is a door that supposedly opens with a round key, the door was open when I arrived (probably opened by a button or lever on the level), but the round key could still be used in the lock.

The stairs at the entrance of the castle (the last level) do not work and you can access the castle (fortunately there was the solution with the console in the nexusmods forum).

I forged all the essences and I have a power gem left over, which I found strange, will this power gem be useful for something I don't know?

I have yet to discover these epic items: water armor helmet, air cuirass armor, air boots, where are they?

There is a mysterious note in a chest south west of AISPRIN, with some X and O symbols, it looks like all possible combinations of something, what is it?

I am missing a treasure, what level is it at? Below is a list of everything I have discovered.

- city veroten (1 power gem, shrine of earth, 1 treasure).
- city cellars (skeleton figurine).
- river meanders (forge of earth, 3 treasures).
- mines upper.
- mines middle.
- mines lower (1 power gem, crowern figurine).
- mines deep (nexus teleporter).
- mines low deep (1 power gem).
- witch tower ground (nexus teleporter).
- witch tower middle.
- witch tower top (1 power gem).
- temple of the snake (1 power gem, nexus teleporter, snail figurine).
- rotten swamps.
- tomb of terror (1 power gem, nexus teleporter, ogre figurine).
- darzog's tower ground (nexus teleporter).
- darzog's tower.
- darzog's tower top (2 power gems).
- great lake (1 treasure, in progress).
- cave of illusions (nexus teleporter).
- cave of illusions middle.
- cave of illusions low (1 power gem, forge of water).
- ruins of a river city (1 power gem, shrine of water, nexus teleporter, 1 treasure).
- destroyed mage ville.
- city of night shadows (nexus teleporter, forge of air).
- magic tower ground (nexus teleporter).
- magic tower.
- magic tower top (1 power gem).
- sunny beach (1 treasure).
- volcanic cave (1 power gem, nexus teleporter, forge of fire).
- sultry desert (1 treasure).
- mysterious sphynx (1 power gem, nexus teleporter).
- mysterious sphynx cellars (green gem, blue gem, red gem).
- mysterious sphynx top.
- gine's castle (nexus teleporter).
- gine´s castle cellars.
- gine´s castle middle.
- gine's castle top (1 power gem).
- aisprin (2 power gem, 1 treasure, shrine of fire, meteorite, nexus teleporter).
- pit of sacrifice (ice guardian figurine).
- graveyard (1 treasure).
- dungeon elemental (1 power gem, also two important items: horn, water flask).
- barlock tower (2 power gems, nexus teleporter).
- barclock tower cellars.
- barclock tower top (forge of balance).
- sandweis (1 power gem, shrine of air, nexus teleporter).
- sewers of sandweis (important item: flute).
- necromancer's lair (1 power gem).
- cellars of the real castle.
- royal castle (2 power gems).
- the top of the royal castle.
- mountain peaks (2 power gem, 1 treasure, death shrine, physicality shrine, spiritually shrine, life shrine, 5 pieces of armor of spiritually).
- dark woods (2 power gems, 1 treasure, forge of life, nexus teleporter).
- temple of water snake (3 power gems, forge of spiritually, 4 pieces of armor of water (probably 1 more?)).
- snowbound crater (2 power gem, forge of physicality, 1 treasure, nexus teleporter, 2 pieces of armor of air (probably 3 more?)).
- ice settlement (2 power gem, scope, cursed compass, 5 pieces of armor of life).
- pyramid is the foundation (1 power gem, forge of death, 3 pieces of armor of the death).
- pyramid the mainhalls (2 pieces of armor of the death).
- pyramid top (1 power gem).
- castle of the khamon-koul (final boss).