Expansions

Perfect World International was first released as an Open Beta on 9/2/2008 (see this thread). Since the game was not reset once the Open Beta ended, this is considered the official release date of the game. Since then there have been a couple of major expansions to the game, which are listed below.

For the background story for Perfect World and each of its expansions see the Story Background page.

The Lost Empire

File:PWI Lost Empire logo.png

Released: 12/2/2008
Links: patch notes / expansion page

Added level 79 and 100 skills for each of the original six classes (archer, barbarian, blademaster, cleric, venomancer, and wizard).
Added the Chrono Quests and past maps.
Added world bosses and card bosses.
Added Warsoul weapons.
Added legendary venomancer pets (Baby Blazing Phoenix and Baby Hercules).

Age of Spirits

File:PWI Age of Spirits logo.png

Released: 5/13/2009
Links: patch notes

Added genies. (Many changes were later made to genies in the 9/15/2009 patch.)
Added auto-pathing to quest locations and the "Find Quest" option in the Quests window to find new quests.

Rising Tide

File:Example.jpg

Released: 12/16/2009
Links: patch notes

Added Tideborn lands (three new zones) and assassin and psychic classes.
Added the Raging Tide PvE server.
Added the Palace of Nirvana.
Added a gear upgrade system for high level gear.
Added Public Quests.
Added Marriage Quests.
Added Tidal Protection Charm Quests.
Added Account Stash.
Added TAB targeting.
New venomancer pets.
Added custom key settings.

Genesis

File:PWI Genesis logo.png

Released: 3/2/2011
Links: patch notes / expansion page

Added Earthguard lands (four new zones) and mystic and seeker classes.
Added Faction Bases.
Added faction diplomacy feature.
Added Divine Contract daily quest.
Added Runecrafting skill.
Added a leveling guide that pops up when you hit a new level (unless disabled at level 21 or higher).
Major user interface update.

Descent

File:PWI Descent logo.png

Released: 2/15/2012
Links: patch notes / expansion page / pre-release news

Added Morai, a new level 95+ zone with new quests.
Two new dungeons, Endless Universe and Murid.
Added the three orders: the Order of Corona, the Order of the Shroud, and the Order of Luminance. The orders provide:

Additional skills

New gear

Pets unique to each order

Some existing skills rebalanced (see patch notes).
Added rare veno pet, the level 101 Ancient Derjan's Hatchling.
New Lucidsilver Envoy and Lucidgold Envoy daily quests and Treasure Hunter daily quest.
Max squad size increased from 6 to 10 (not including old instances).

Sirens of War

File:Perfect-world-international-sirens.png

Released: 11/14/2012
Links: patch notes / expansion page / pre-release news / more pre-release news

Nation Wars
Realm of Reflection
Added auto-potion function
Rebalanced skills (see PWI: Sirens of War - Skill Changes for details)
Improved many level 30-70 quests (more rewards, lowered kill requirements)
Various dungeon and Spiritual Cultivation quest tweaks
New level 50-80 quests
Seasonal quests

Rising Call

Released: 5/19/2013
Links: patch notes / release news

Rising Call was apparently a sub-expansion to Sirens of War and does not have its own logo.

The Rising Call content update includes:
Expanded Nation Wars regional map
New Nation Wars battlefield maps: the Crystal Contest and the Bridge Battle
New venomancer pets and evolution system
New Soulgem Conversion feature at PW Promotions Agent
Updated and revamped high level instances (Seat of Torment and Abaddon)
The powerful and potent Meridian System
New quests (Seasonal Harbinger and quest for ★★Matchless Wings)
New fashion weapons
Event Notice Billboards added
Other fixes and improvements

Crimson Imperium

Released: 9/25/2013
Links: patch notes / release news

Crimson Imperium was apparently a sub-expansion to Sirens of War and does not have its own logo.

The Crimson Imperium content update includes:
Title System: Earn titles within the game that will reward you with a variety of buffs.
Attendance System: Earn rewards just for playing. Consecutive days played will result in better rewards.
New Event: A Legendary Phoenix has been spotted and is reportedly carrying some rare loot.
Perfect Match: An in game social networking system to help you connect with new friends or partners to aid you in combat.
Nation Wars' Territories: Now reduced down to 128 territories but still retaining the new maps from the last update.
Commission Shop: A new shop system that allows you to browse items on sale from anywhere in the world.
Optimization Changes
New Quests
And more (see patch notes link above for details)

New Horizons

File:PWI-New Horizons-logo.png

Released: 12/18/2013
Links: patch notes / release news / pre-release news

Reawakening System: Take your Lv100+ character to new heights be reawakening them!
War Avatar System: Collect War Avatar cards to power up your character's stats to a new horizon. (preview 1, preview 2)
New Zones - Primal World: New experiences and treasures await those who are brave enough to enter this world Pan Gu discarded.
New starting zone - Place of Origination: Get familiar with the origins of Perfect World to understand the threat that it now faces!
New skills: All classes have new skills to push their abilities even further than before as well as furthering Sage and Demon versions.
Revamped starter experience: A smoother starting experience awaits all, taking you through the new story and giving players an earlier taste of the power to come!
Cultivation Assistant: Automatically set up your attacks to level up your character even faster.
History Advancement System: Change the state of the world by progressing through world-wide objectives as a community!
Event Calender Upgrade: Browse through all the events in the game, queue up for a squad, and even teleport straight to the entrance!
UI Improvements: With an in-game assistant that provides all necessary information on anything clicked on the screen, such as item recipes and skill descriptions, the New Horizons user interface is the best PWI has ever seen!
And more (see patch notes link above for details)