Grimrock

-For the southwest part of level 4 that you can reach from below;
Notice there are two corner rooms in the area, with two doors and a pressure plate in each. The one the crab starts in fires the lightning bolts, but that isn't helpful in this case. You need to get the other one active by similar means.
Also, you will find a shortcut there soon so no need to hike back.

-For the goromorg, he likely went into the teleporter and is somewhere on level 3. You will need to track him down a get his key.

-For the plates, it is a large puzzle. You do have to throw things on them, but won't be able to from where you were standing. The cell bars will never move, but you can get around them.

There are 3 plates on the rooms you described. One of them you can mantain pressed with an object, but I don't know what it does. the other two makes the south-central demon head shot lightning bolts. There's also a demon head on the west side with no hole to get the bolt at the end. I noticed that sometimes the central head shots a different ray, that makes the pit on the top-center close but it's a fast event. The problem is I found the bolts too random, and thy even stop randomly.If you can point me exactly what to do with tis room I´d be grateful.

I hope the goromog don't mess my entire game, since I need a key he possess. Tried to kill him several times, with my heroes with full strenght but got no luck.

Also, this central room with the crabs is still a mystery, I can't see how to access it now. Abouth the big puzzle you mentioned, I hope I can figure by myself once these problems were gone.

But I have to tell, you did a hell of a job with this module, so far it's the more balanced I played, and the best. I hope I can still continue it till the end.

The plate in the other room fires the different bolt, which is the one you want. You cannot maintain it with an object though, it is one fire per trigger, so you need to trigger it over and over. You need to lure a monster in there to step on it while it's trapped in the room, like the crab was stuck in the other room causing lightning bolts to fire. Then you can stand next to the open pit, wait for the monster to trigger the plate and grab the loot while the pit is shut for a short time.

Where did the goromorg end up at? Not sure I understand issue, but try using ranged attacks and dodge while on corner squares if you can't lure it into a room. You could also attempt to teleport onto it for instant kill.

Thanks for the kudos. You can continue, I will always help.

The demon firing a bolt with no hole, keep it in mind when u be higher
The room u cant access you will access later dnt waste time there
You have to coordinate to grab what is in the alcove when trap closing
ABout goromorg, yes it is truely tough but u can do it and it will take time... Try to circle in 2*2 square, u can hit and move in a circle... Believe me it is possible
Dnt give up for sure as this mod is just fantastic

How can I reach the alcove on the north-west side of the moving plates room on the third floor? I could open it with a secret button on the wall, but no matter what combination of steps or how fast I run I always fall in some hole without reaching it. There's some trick?

First off, that spot is a secret not necessary to complete the game so you can ignore it if you want. But if you already reached the secret button that opened it, you should have been over there already in order to throw onto the 4th plate below. You should be able to use the same path back.

You can reset the plates below to time them better by taking the item off and putting it back on. This can take some experimentation. However, with the southwest plate you can just remove the item and keep those pits either all open or closed since the pits it affects were all originally open. Having those four pits permanently closed can help a lot.

I´m trying with the four plates pressed by objects. I noticed that from the north-east part of the room below you can take of the objects from the plates in the adjacent sectors, since the objects are placed near the bars, and I was wondering if this is the trick. Well, since you said it's just a secret I think I let it go for now. I´m trying to figure what to do on the second floor. Killed 3 ogres and got two skulls, and one key that just opened a section. Also, found the note with the message "behind the left eye" or something like that. Noticed a button but so far nothing happens.

Did you remember the demon on the lower level? (this has nothing to do with your question )

About the left eye, it is something that you will find later no stress just keep ur eyes open if I can say that ... I fully agree with you about this mod, its a pure jewel... I am restarting it tonight with new optimized party and higher difficulty level...

I remember the demon, you mean the one with holes in the eyes to put the blue gems, right?