Before I begin, since this is my first post I'd like to say that having played through legend of grimrock several times I have enjoyed it thoroughly. Thankyou for bringing out this piece of an otherwise sadly dead genre.
However,
I do not see much discussion on where we can go from here and how to spice things up with the way combat works. The devs were very faithful to the way the old style games played and it was a wonderful nostalgia trip. But I feel that a chance to add to it was missed out and would like to put forth a few issues and ideas.
We all know that taking on single stacks of enemies in any greater than a 2x2 cell results in an easy merry go round until the poor thing is dead(in fact sometimes the AI seems to realize the futility of it all and just sits there sadly not moving for long periods of time). Could there not have been at least one or two creatures capable of attacking diagonally? Sure it would not have fixed any core issues but it would be one more interesting thing to take into account. On that note it is surprising that large creatures such as the ogre do not have any sort of arcing sing attack capable of hitting all the tiles in front of it. This would have made it a far deadlier foe than it is now and really make a player think about how to engage such a threat. Naturally not all creatures should be able to do this and classic swarming still gets the job done, but this would have added that much more depth to your encounters in the depths.
Onto magic. The rune system is a welcome sight but feels very much underused with very few spells available, reducing the amount of experimentation available and further limiting things to a particular tree. Due to this same limitation, most of the spells are mechanically clones of one another simply in a different flavor/color. Now we can discuss ideas for new spells all day but adding to much would cause the wizards and mages to be the stars of every game and overshadow the other classes in complexity in all runs so I will just say to include a few to take into account tiles other than the ones directly in front of you. But I would recommend giving the mage access to the basic spells of the other trees in weakened forms(after all, they aren't specialized in them) so they are not rendered worthless when facing resistant creatures. Balance wise by only gripe with the overall balance is that air gets an extra spell, the invisibility spell. This grants the preference to the air tree for simply having more versatility(also remember it is the highest damage tree) than the others. At least grant an extra spell to the other trees to balance it out. Earth in particular only being effective against the living and requiring keeping them still(something that most certainly will not be happening often), why not give it something to compliment this style?
Finally to the dungeons themselves. The current design is purely classic and I have already seen others asking about multiple elevations within a level. Since it is already being discussed i am simply just bringing it to attention again.
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Something else that just came to mind. None of the creatures in the game apear to heal at all, especially apparent if you face the slime maze early on. Here it is readily apparent that you can hit a slime a few times, retreat, heal, and return to finish off the injured abomination. Introducing regenerating and or creatures capable of healing themselves would also add much to depth I feel.\
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I would be interested to hear other's ideas and hope some of these things will be addressed in one way or another.