In Castle of the Winds 2, you can either import your stats and items from your Castle of the Winds 1 file, or start a new game. If you start a new game, you'll start out at Level 7 with 75000 C. I recommend taking Shield, Detect Objects, Light, Identify, Neutralize Poison, Heal Medium Wounds, and Lightning Bolt if you're gonna do it this way. Though personally I think it is easier if you play the first game first.
Also make note that all the dungeon floors in this game (with the exception of the top floor) are randomly generated.
You'll find yourself in a new town. First try to get entrance to the castle right next to you and you'll be denied. There are 10 shops in this town; 2 Armor, 2 Weapon, 2 Magic, 2 Utility, and 2 Item. If you're just starting out, buy yourself some better equipment. If you've imported your file, then still look for better equipment.
Also in some of the shops there will be Draughts of Gain. If you see one, buy it and use it. It will permanently raise a stat of yours. These will always come in handy. Also, don't be fooled by Potions of Lose either. They look similar to the Draughts of Gain, but they have a red symbol instead of blue.
Also note that there is more enchanted equipment to buy compared to the first game. To find out which one is the best to get, right click on the item. Look for armor that "strongly" or "very strongly" increases your armor value. Weapons should be the same way, but try to use the highest weapon class possible. Also don't buy an enchanted weapon unless it increases both damage and hit %. One more thing. If you're gonna get a 2 handed sword, make sure you get a Ring of Protection or make sure that the sword increases your armor value, because you can't use a shield with this weapon.
A few things that you MUST get as soon as you can are a Utility Belt, an Enchanted Pack of Holding (preferably Large), and Enchanted Boots of Speed.
Once you are all set, head to the northern exit and into the Castle of the Winds. Kill all of the monsters and then head to the throne room to talk to your Grandfather, King Lifthransir. He tells you that the Helm of Storms was stolen and that he needs it back. He goes on to explain about a demon named Sultur who stole the Helmet. You now know what you must do.
The Castle of the Winds:
Take the stairs from the top floor to the first dungeon floor. Your strategy should be this: Go down a floor, use Detect Objects, get each object, exit back to town, repeat. Rune of Return works good, so if you have it, use it. If not, try to gain a level to learn it or else just buy the book. And when you return to town, check each of the stores for better weapons, armor, etc. and check for Draughts of Gain and spell books. Also head to the Temple of Odin and see if you need any of your stats restored. Believe me, if you fight Wights or Wraiths, you'll need to check.
Anyway, battle your way down to the 4th floor. You'll hear a man screaming from the distance. Save it here and look for him promptly (if you take too much time, he will be killed). Once you find him, kill the Huge Ogres and free him. He will tell you more about the castle and of Sultur. Head back to town. Now try to enter the castle. The Jarl this time will speak to you for rescuing the prisoner (you did rescue him, right? Else load and go again). He will give you 100 gold pieces. Shop around and then head back to the dungeon. Hopefully by now you know Rune of Return.
Continue going until you reach the 6th floor. What you're looking for here is a lair of Wolfmen and wolves. Kill them and finish off the floor. Continue and when you reach the 8th floor, you'll run into a lair of Bearmen. Kill them and continue. Continue to the 11th floor and you'll run into a group of Wizards. Kill them and return to town. Talk to the Jarl in the castle and he will give you Enchanted Gauntlets of Slaying.
Now at this point you'll want to have in your inventory the 3 elemental necklaces. Also it would be handy to have the 3 Resist Spells. The Very Old and Ancient Dragons live further down, and if you can't resist their element, then you probably won't last long. Also make sure you're keeping all the Essences of Restore and Elixirs of Healing. Don't use them yet, save them. Also Distillations of Greater Restore Mana can come in handy on your Utility Belt, as can Scrolls of Map Level. Also, if you're real lucky, you'll have a weapon that is strong against Giants (I managed to get a Bastard Sword that was strong against Giants, and very strongly increased Damage, Hit %, and Constitution... probably the best weapon I've ever come across, but since the game is random, you might not get this weapon).
Keep making your way down. On the 14th floor are some tough Castle Wights. Try not to let them drain much of your stats. Go down to the 15th floor and clear out the monsters there. Head back to town where the Jarl will give you an Enchanted Meteoric Helmet. Make sure that you have the strongest equipment that you can get, the best pack, the best potions, and of course the Draughts of Gain (hopefully you're still using them). Also by now you should be around level 9 or 10 and have learned the spell of Healing.
When you're ready to go again, make your way down to the 16th floor. Use a Scroll of Map Level and look for a Throne Room (or find it if you don't have one). Once you find it, you'll be face to face with the first Giant King, the Hill Giant Utgardhalok. He's not overly tough if you can get to him one-on-one, because he is backed up by like 5 or 6 Hill Giants. The best thing to do is lure them to a narrow passage where you can fight one at a time (making sure that they can't attack you diagonally as well). Use Healing if you need it and finish of Utgardhalok.
Just a note on the 17th floor there is a room with a hidden glyph in the middle that will activate about 6 statues. The statues are not too tough, but they can be annoying. Just be careful of this room.
On the 18th floor, use another Scroll of Map Level. Find the Throne Room again and go there. This time, you will run into the Stone Giant King, Rungir, and a few Stone Giants. Follow the same strategy in killing him as you did with Utgardhalok and he should be a breeze.
On the 19th floor has a pool of Water Elementals. If you can handle them, it is good experience, else try to just move to the next floor.
Head to the 20th floor and yet again use a Scroll of Map Level. Look for the Throne Room and face Thyrm, the Ice Giant King. Again, use the same strategy of ducking into a narrow passage and them proceeding to pound them to the ground. Continue on once you beat them.
The 21th floor has a room with a pool that houses Fire Elementals and Old Dragons or greater. If you can use Resist Fire, or have the Charm of Resist Fire, go for it. Else just move on.
The 22nd floor contains the last Giant King, Thiassa, the Fire Giant King. Again, same strategy. Defeat him and head back to town. Talk to the Jarl one last time and he will say that you're close to Sultur.
Make your way to the 24th floor. This is the last floor before Sultur. Clean it out then return back to town. This is your last chance to shop. Buy Elixirs of Healing, Distillations of Mana, and Essences of Restore. Also, you'll want to have some kind of equipment that either gives you resistance to Fire or Lightning. If you have a piece of equipment that does that (shield, armor, weapon, whatever), then use the necklace of the other element listed. If you can't get a piece of equipment that does that, just equip the Charm of Resist Fire and have the Resist Lightning spell handy. Also, hopefully you have one more Scroll of Map Level. Be around Level 13 before going on any further, with Healing, Resist Lightning, Resist Fire, Shield, Ball Lightning, and Detect Monsters for spells.
The 25th level contains all of the tough baddies of the game, including Sultur. When you arrive, use the Scroll of Map Level, then followed by Detect Monsters. Check out your map and look for Sultur. Reach him to start the final boss battle.
Sultur will always be surrounded by his minions. Don't worry about them just yet. Worry about Sultur. When you first see him, cast your Resist Lightning Spell (if you need it, you should have the Charm of Resist Fire equipped). If you're still at a distance, nail him with Ball Lightning. Lure him to a narrow passage and attack him. Heal when you need to and keep attacking. Save after every round of battle you face with him. The reason being is that when Sultur starts to run out of life, he will Vanish and warp to another part of the floor, fully healed. If he does that, load and hit him with Ball Lightning or something. Keep up the attacks and Sultur will die, dropping the Helm of Storms.
It isn't really the ending. Pick up the Helmet and equip it. You'll have resistance to Fire, Cold, Lightning, and Drain Life, but you can't use Rune of Return to exit, so you have to walk up to the first floor. Use an Essence of Restore if your stats are drained. If you don't have any, drop the Helm of Storms on the floor and use Rune of Return to go back to town.
Making sure you have the Helm of Storms, walk all the way back up to the top. It shouldn't be too tough if you're around level 13. Once you make it to the top, talk to your Grandfather. He will be pleased with your quest and will reward you with the throne to the Castle of the Winds.