I am a very new player to the game but since I started I have learned a few things about playing.
I will post the few things I do know so far, but please keep adding to this and we will have a great little section that should help one another with the game.
General Game Play Tips
1. Use shortcut keys to bring up items in the game instead of pushing your mouse around. This is epically true for the Journal Book that requires you to go to the far left of the screen to bring up with the mouse.
This list is in the PDF Manual, but I reproduced it here.
Journal
1 = First Page
2 = Notes (most recent)
3 = Runes (first page)
4 = Clues (most recent)
5 = Items (most recent)
6/Tab = Map (current map)
Home = First Page current section
End = Last page current section
Page Up= Page back in Journal
Page Down = Page forward in Journal
Game Controls
Esc = Options Screen/Cancel
O = Game Options
I = Inventory Scroll
M = Mystic Mirror
J = Journal
Enter = Pause (speech)
Space Bar = Cancel
F2 = Save Game
F3 = Subtitles on/off
F4 = load Game
F5 Lower Music Volume
F6 = Raise Music Volume
F7 = Lower Sound Volume
F8 = Raise Sound Volume
F9 = Voices on/off
F10 = Quit Game
F11 = Brightness Control
F12 = Mouse Sensitivity
Inventory
Home = Top of Inventory
End = Bottom of Inventory
Page Up = Up 5 Items
Page Down = Down 5 Items
2. When fighting Bugs, throw rocks at them as you keep backing up. This way you can kill them while taking no damage at times.
3. You can kill enemies standing on the other side of a door if they are in the middle of the door way. Just throw rocks in at the enemy and it will die. I know it is an exploit, but if you are low on health it may be viable.
4. Check the stones in walls everywhere. You never know when you will come across a hidden item or control switch.
5. Make notes on the map letting you know which stairs lead to a given area. I have named areas in the Journal on the first floor such as "Area 1," Area 2," etc. Then I noted in the Journal while on the second floor down stairwells with notes such as "Stairs to Area 1," etc.
6. Always keep 2 weapons in your hands at all times while traveling the dungeon. Well, unless you have a shield in one hand that is! :o)
7. Check trunks you cannot open with the keys you find; they may just work! :o)
Anyway these are few Tips to get started with.
Enjoy the game, and take your time, it is half the fun.

Your welcome. I have really been enjoying this game very much.

8. Walkthrough Wall
I found a wall that you can walk right through in the game.
It is located on the level where you meet The Great Wahooka. As you travel around you come to a place in the dungeon where you either go Left to the Sewers (there is a sign on the wall saying so), or you can go Right and you run into 2 or 3 Goblins.
Go right and kill the goblins. Then go straight down the hall and there is a left hand turn in the dungeon...DO NOT TAKE THE LEFT.
Instead go straight through the wall in front of you instead of taking the left. You will pass right through the wall and end up on the other side of it.
Beware though, you will meet 2 very tough goblins that tell you to leave and then they run away. But as you go toward them they will make short work of you. I ran past them and found what appeared to be a Sewer Shaft.
I hope this made sense. If not just ask and I will try to help.
Have fun and post your findings here and we will end up with a rather good database for the game.

Nice Post. For those who are just starting, don't sweat it if the journal isn't working. It's not supposed to at first. You need to find it early in the game.
<SPOILER --- EASTER EGG (?) -- BELOW >
If combat isn't your thing and you want to breeze through the upper levels, then here is a trick for you. It only works if you are just starting the first floor and haven't gone down to the second floor yet. When you get to the door to go down, where Thera is hovering, you have to pull a lever. Pull the lever three times, down, up, then down. Do not go down yet. Go back and check the walls of the first floor for a movable brick that wasn't there before. Behind the brick is another lever. Pull this lever to open a hidden passage. In the hidden passage is another hidden brick. Open that brick for a very powerful dagger. This will make combat a breeze at the start.

Don't forget to use the orbs. When you pick up the first orb it says something like, "I should look at this more closely". It's not very obvious but this means you should drop it on the floor. The first one will show you a small portion of the map around you. This saves you from having to constantly try to walk through walls to find secret passages.

Don't attack flying insects or their nests and they wont attack you.

Here's a question for people who've played the game before: How's the skill progression curve? It seems fairly slow to start with, to the point where I'm wondering A) if I should try and find a place to grind strength, agility, and sword skills and B) if I CAN grind them efficiently or if I should just soldier on and not worry about building my character.

Attack everything that can be attacked (tables, barrels, monsters) and you will gain skill with the type of weapon you use. Enemies are not randomly generated so power leveling isn't possible until you get to the Dwarfish realm where there is a large stone that you can keep attacking as much as you want to gain skill.

Yeah, I figured the first part. My main concern is that I tend to be a "jack-of-all-trades" type, and so was planning to alternate dagger-sword or dagger-hammer for this first bit of the game in order to even up strength and agility building. If enemies aren't randomly generated I won't worry -too- much.

Wow these are some great tips. I actually found a few areas where enemies constantly respawn. One is first or second map (don't remember) but ants will continually come out of a pipe. The floor after, snakes will continually come out of the pipes.
I also read in the manual that enemies have 'weak spots'. What does that mean? Does it mean there are spots I should click to do more damage, or does it simply mean some enemies are weak vs. slashing, piercing or smashing (found that to be true vs. slime blobs... slashing swords did damage, everything else doesn't do anything).

THANKS! I knew there was a way to get to he current map (aside from paging along) but I couldn't remember it
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The deciding factor for improving your stats is the number of melee hits you score. Therefore I'd wipe out all monster respawns (none of the respawn points is endless), equip party members with two shields instead of a weapon unless it's getting too hard, use spells only for healing (don't use a healing well if you can reload mana, use healing spells and improve your casting skills instead) and hard battles, don't throw rocks if you don't need it.
Using fast weapons will improve your character faster than using slow high damage hammers, but you might need some hammer skills nevertheless (get the stone hammer) to hurt some tough monsters without spells.

Copied this down while waiting for the game to download. Really looking forward to this one. Thanks for the info.
Great site, GOG guys!

Don't forget to post your insights after you play a bit! :o)