All twenty quests will be available in single and multiplayer. As with Diablo I the quests will be random and available to all five classes. Quests can also be either day or night specific. Each set of quests must be solved before you can progress on
to the next town although some quests require you to visit other town settings through teleports.

With Diablo I and Hellfire your reward for completing a quest was usually an item of some sort but more thought has gone
into the sequel. Sometimes you will also earn the trust of an NPC who in return will assist you in your next quest.

Quests will also enable you to pick up valuable experience points and discover more of Diablo II's story line helping draw
you further into the game's history.

Act I

Andariel prepares to swipe Your first quest starts in the Sisters of the Sightless Eye Monastery in the mountains (Sisters Burial Ground quest) where you will battle Corrupted Rogues, finally facing the mini boss Andariel . Throughout each of the four acts there will be subquests which furnish you information needed to complete the main quest, in this case the defeat of Andariel.

One such subquest, Field of Stones will see you having to revive a circle of mystic stones, long ago used by mages to teleport to remote realms. Once restored, the stones will enable you to travel back to Tristram (now burnt to the ground) to engage the help of Cain the Elder. Succeding in this quest will allow you to take Cain back to the relatively safe haven of Act one where he'll be able to ID items for you. Some quests will involve you protecting a town against the marauding hordes from the depths. This could also earn you favour with certain NPCs who may later help you for a lowered fee.

Having defeated Andariel at the end of Act I you will then journey to the second Act by means of caravan through a pass accompanied by Warriv to the city of Lut Gholein in the east.

Act II

Your primary quest here is to locate the lost tomb where Tal Rasha was buried, and is the area that served as the birthplace, centuries ago, of the Horadric Orders, the mage clans who originally captured the three Prime Evils, Diablo, Baal and Mephisto in soulstones. You must prevent Diablo from freeing Baal from the Tomb. The Tomb entrance can be found carved into a mountainside.

The ultimate objective here, as far as I can gather from numerous conversations with Blizzard is to annihilate Baal, Diablo's sibling. You will also face their other brother Memphisto, I would hazard a guess in Act III which would leave Diablo himself for the end of Act IV. Saying that, there are mutterings that you won't have to wait until game-end to meet Diablo, so this should be taken as speculation on my part. Rest assured you will be facing the gruesome trio, officially known as the Prime Evils, on your quests.

A couple more quests where only the title is known are Den of Evil and The Forgotten Tower.

And when the quests are done?

Once you have finished the game, quests and all, the game is by no means over. As in Diablo I, Diablo II will have its difficulty levels which will work much the same way. Max Schaefer confirmed in our interview at ECTS "My guess is we're going to do difficulty levels just to handle the varying levels of players. Once you've played for a few months, your character is super strong and you've beaten Diablo it really makes sense that you have a difficulty level to increase the challenge". In addition to that Bill Roper has flaunted the proverbial Red Rag to the hardened players claiming that "It will be very difficult to get beyond level 50, but there is no hard cap on experience levels". With a promise of cheat-free Battle.net games this will truly be an achievement.

As well as set quests you can set your own personal quests also. Finding the Holy Shield of Defence, for example, and deciding that these are the attributes you are after will set your own personal quest to find a Holy breastplate of Defence and the Helm or mask to match. Getting all three isn’t just some fashion coup though, your perseverance for a full set of equipment will be rewarded with a healthy bonus, not to mention the pose-factor when hanging out on Battle.net.