You will start your long and dangerous adventure in the small Rogue Encampment which the rogues established after they were forced out of their Monastery by the evil and corrupted rogue Andariel. The Rogue Encampment lies in the middle of a the wilderness which is infested with monsters who has risen from the monastery. Your main mission in Act I is to help the rogues clear the Monastery and finally get rid of Andariel so they once again can live happily in their Monastery.

Now in the beginning of your long adventure your character is very weak so the first thing you should do is to walk around in the camp so you get to know the place and it's inhabitants. Make sure you visit and talk to all the NPC's so you find out what's going on and what they want you to do :

Akara:
She will instantly regenerate your health and mana points each time you talk with her.
She is the only one in the Rogue Encampment selling healing potions, scrolls, magical staffs and wands.

Kashya:
She will offer her best rogue mercenaries for you to hire, but only after you finish the Blood Raven quest!

Charsi:
She is the blacksmith in the camp and offers weapons and armor for buying and selling. She also sell magical items. She also repairs damaged weapons and armor for a gold fee.

Gheed:
He is the second salesman in the camp, but he sells a items with a bit better quality than Charsi..

Warriv:
He will transport you and Deckard Cain to the east after finishing the sixth quest in Act I.

Deckard Cain:
He becomes available in the camp after you finish the third quest of act I. When you rescue him, he'll identify items for free and provide helpful information as you progress through the game. If you skip quest three, Cain will automatically be rescued once the sixth quest is activated, and he'll charge for item identification.

Just outside the Rogue Encampment you'll find the Blood Moor. This area is swamped with quill rats and the living dead, zombies. You may also sometimes encounter a few Fallen ones, but they rarely appear this early in the game. Kill everything in this area to gain some needed experience before you venture into the "Den of Evil", a small cave which also is the first quest of the game!

Also in the Blood Moor is Flavie, a rogue mercenary guarding the road between the Blood Moore and Cold Plains. If you talk to her, she will tell you if you have enough experience to withstand the bad monsters in the Cold Plains.

Here the monsters are a bit tougher than they were in the Blood Moore and it also contains a Fallen Camp which is filled with Fallen, Fallen Shamans and the unique Fallen Shaman boss Bishibosh, a fire-enchanted monster with magic resistance. The magic resistance gives him a 75 percent resistance to elemental attacks while fire enchanted gives him 75 percent resistance to fire damage. He also has a double to hit chance, additional fire damage and the ability to raise the Fallen Shamans, who has the ability to raise the Fallen. So unless you want to kill Fallen forever, I suggest that you try to take out Bishibosh first, then the Fallen Shamans and finally the Fallen ones.

There should also be a cave in the Cold Plains called the Cold Cave which is a 2 level dungeon. The first level is very big and contains some Fallen Shamans and som Fallen Warriors together with the unique boss Cold Crow, who is a cold enchanted dark ranger. Kill everything in the first level before proceeding to the next.
The 2. level is always the same in each game and contains two unique monsters, three Fallen Shamans and their followers, a few Skeletons, Hungry Dead and Dark Rangers. Complete this cave for some extra experience!

You'll also find the exit to the Burial Grounds where the second quest in the game takes place. This is where Blood Raven is busy rasing zombies.

Also in the Cold Plains is the exit to the Stony Field

This is a small area with a graveyard. In the middle of the graveyard is Blood Raven who is the goal of the second quest in Act I called "Sister's Burial Ground". The graveyard is also filled with zombies and skeletons, so it is a hard area even though it's very small!

It also contains entrances to the crypt and the Mausoleum. Both are one level dungeons, and each contain a unique boss and a magical chest.

You can gain tons of items and experience in the crypt which is infested by undead monsters. Check out the undefiled graves and destroy barrels for treasure, grab items from weapon racks, armor stands and chests. The magic chest is guarded by the skeleton BoneBreaker, an extra strong unique with magic resistance. Kill him for a nice reward.

This is also an excellent place to level up and gather items and treasure. It's infested by the same monsters as the crypt so you should have no problems going through it.

Search the Stony Field for Rakanishu, a unique lightning enchanted and extra fast boss. Extra fast doubles attack rate, and lightning enchanted supplies lightning damage while making him 75 percent resistant to lightning attack. His lightning damage is very dangerous, since every time you hit him, he releases a big chunk of lightning bolts which do serious damage, so be careful! Trying to help him take you down is other Fallen Shamans and a crowd of Fallen ones.

If you explore the Stony Field you will find a ring of big stones. Those are the cairn stones and are part of the "The Search for Cain" quest.

Also in the Stony Field is the Moldy Tome which activates the "The Forgotten Tower" quest.

To proceed from the Stony Field you have to find and enter the "Underground Passage" which is a cave. It is a rather big cave, with lots of monsters so it might be hard to get through. In the first level of the cave there are 3 exits. The first exit leads back to the Stony Field, the second exit leads to the cave level 2 and the third exit leads to the Dark Wood.

If you decide to complete the third quest in Act I called "The Search for Cain" you will gain entrance to Tristram from the Cairn Stones.

Tristram is a very dangerous place as it is infested with Goatmen, Fallen Shamans, Fallen ones, Skeletons and Zombies. It also contains a few unique bosses one of which you might recognize!

Make sure you search for Wirt as he has lots of gold for you if you find him! You can also take his leg and use it as a weapon if you want to! The leg is also used as an easter egg in the game, so don't throw it away if you want to have fun later in the game!

When you walk around in the Dark Wood, you will encounter the Tree of Inifuss which is a part of the "The Search for Cain" quest. It is usually surrounded by Fallen Shaman, Fallen ones, and a unique boss called Treehead Woodfist who is extra fast and extra. Extra fast doubles Treehead's attack rate, while extra strong increases his damage and to-hit percentage by 25.

From the Dark Wood you'll find the entrance to the Black Marsh

In the Black Marsh you'll find "The Forgotten Tower" which you have to rid of evil to complete the quest. The Tower is a 5 level dungeon with the Countess found on the fifth level. The Tower is very hard and very long, but you'll find tons of gold and equipment, and it's a great chance to level up and gain experience!

The Countess is fire enchanted which gives her fire damage and a 75 percent resistance to fire attacks, so you might want to wear some equipment giving you some resistances to fire, or it might be a tough fight!

Also in the Black Marsh is a cave you can explore for some extra gold and equipment, and of course gain some experience!

From the Black Marsh you gain access into the Tamoe Highland

The Tamoe Highland is the last part of the wilderness as this is where you gain access to the Monastery, the place where Andariel is making evil plans.

In the Tamoe Highland you'll find a pit, which is recommended to complete in order to gain some experience and extra gold and equipment from which you can buy and get better equipment

To get to the monastery locate and enter the Monastery Gate which is in the Tamoe Highland

As you might guess, the Monastery is quite big and this is where the toughest of the Act I monsters reside!

When you first enter you'll find yourself in the Outer Cloister. Here you'll find the easiest of the monsters that awaits your arrival, so if this place is giving you a hard time, I suggest getting more experience or better equipment. Maybe you should get both?

From the Outer Cloister you'll gain access to the Monastery Barracks! The Monastery Barracks is where the fifth quest of Act I takes place and is called the "Tools of the Trade".

From the Monastery Barracks you'll find your way into the jail level 1. Here you'll encounter Pitspawn Fouldog who is a cursed, cold-enchanted unique boss. Cold-enchanted gives him a 75 percent resistance to cold attacks so if you were cold-enchanted weapons, expect a really tough fight! The jail is three levels in total and from the third level you'll find the entrance to the Inner Cloister

There isn't really that much to do in the Inner Cloister except maybe finding and kill Flame Spike the Crawler who is a unique boss. He is cursed and fire enchanted which gives him a 75 percent resistance to fire attack as well as fire damage. When you get rid of him you can carry on into the Cathedral.

The Cathedral is actually a small place compared to the other parts of the Monastery, but that doesn't mean it's any easier! Inside the Cathedral you'll find Bone Ash, a unique boss who is cold enchanted, extra strong, and has magic resistance. This creates one tough monster so you should be prepared when you want to take him down! You'll also find the entrance to the Catacombs from the Cathedral.

You have finally arrived at the final part of Act I. The catacombs is four levels big and in the fourth level you'll find Andariel who is the sixth quest of Act I which is called "Sisters to the Slaughter". After finishing the quest return to the encampment to be praised like the hero you are from the inhabitants of the camp!