Below are the most popular (in terms of number of players) PC games out there.

World of Warcraft: Wrath of the Lich King

The unique art styles, new-user-friendliness, and those little touches that are developer Blizzard’s hallmark help to explain why World of Warcraft (WoW) has nearly 12 million subscribers.  In fact, this latest expansion holds the record for fastest-selling PC game of all time.  But what does “Lich King” add to a game that’s already so crazy addictive?  Well, there’s the new Death Knight, the game’s first hero class–a sort of combination Necromancer/Warrior. The level cap has been raised to 80, and more overall customization is possible.  Oh, then there’s Arthas, the Lich King himself, one of the most powerful entities in the Warcraft universe…and you’ve got to stop him.

Warhammer: Dawn of War II

Warhammer’s dark, violent, richly-realized gameworld has amassed an impressive following since its introduction to the PC gaming community in 2005, so the appearance of this latest expansion is no great surprise. However, Relic Entertainment’s newest release is no mere sequel–it’s a complete rework of the Warhammer franchise.  Gone is the base building, while RPG elements, such as unit leveling, have been added.  Additionally, there is a revamped single-player campaign, and the fully-destructible environments serve the game play well. One thing that (fortunately) hasn’t changed is the frenetic action and fast-paced co-op play that made Warhammer so much fun in the first place.

The Sims 2

There are so many expansions for this venerable series sequel (and the original game) that it is pointless to list just one entry, but suffice it to say, the Sims games and their add-ons remain ridiculously popular. Released 1½ years ago, The Sims 2 nevertheless stays successful and relevant with a well-placed succession of expansions, the most recent of which is “The Sims 2: Apartment Life”.  This expansion allows your Sims to socialize as never before, and adds new content while not fooling excessively with the tried-and-true Sims formula.

Empire: Total War

The Total War series famously combines the best of classical table-top turn-based strategy with involving, challenging hands-on battles.  The sheer breathtaking scope and spectacle of these battles are a touchstone of these games, and that is unchanged here.  The 18th-century setting was a wish come true for Total War fans, and the much-anticipated 3D naval combat is well-implemented.  Several small augmentations and refinements over the previous releases, such as improved systems on the Campaign Map, make this a notable addition to a distinguished franchise.

Spore

The only title on the list which is neither an expansion nor a sequel, “Spore” may also be a strong contender for most unique PC game currently out there.  Created by those who brought you The Sims, Spore allows you to formulate your own lifeform from scratch, while blending strategy and RPG elements which meld nicely with the cartoonish setting.  A series of progressively more complicated development phases bring your creation all the way from the microbe level to the scope of an entire space colony.  Along the way, your creature will evolve and adapt according to your whims.  Enriched by an extensive online community, the potential for user-created content is significant.