It took one of the most hardcore genres around and made it accessible
In case you weren't sure, "World of Warcraft" is a massively multiplayer online role-playing game, or MMORPG for short. That means it takes place in a huge, persistent world where players run around and do quests with each other, level up, collect loot and maybe even fight each other.
Before "World of Warcraft" came along, the most popular MMORPGs were games like "EverQuest," which were not especially welcoming to new players, comparatively. It was a different time, so expectations were different.
"World of Warcraft" did a better job of explaining the more arcane aspects of the genre and easing newcomers in, even if it wasn't perfect. It's actually a much more friendly game now than it was at launch, too. This is a great time to jump in.
Its world is enormous, varied, and a joy to explore — and it keeps evolving
The original release of the game had two gigantic continents for players to explore, all based on the "Warcraft" series of computer strategy games. Each of its numerous expansion packs has added another sizable landmass, meaning there's a whole lot to see out there.
The "Warcraft" fantasy universe draws inspiration from pretty much every other fantasy universe, so there's a ton of variety around every corner. One playable race lives in a huge, crashed spaceship, while another is a race of zombies that lives in the sewers underneath an abandoned city.
There are also intelligent, bipedal cows and martial artist pandas to go along with your generic humans and orcs. The game's stellar art direction helps bring all of these different races and their respective homelands to life.
It's designed to be as addictive as possible
"World of Warcraft" requires a paid subscription to play, meaning it's designed to keep you playing as long as possible. That may sound like a negative thing, but it's just honesty, and they do it very well.
From the minute you start playing, the game constantly dangles a carrot on a stick in front of you. It could be a new ability, a powerful sword, or a cool mechanical chicken to ride on.
Whatever it is, it's always just attainable enough that you'll say "just one more quest before bed!" Before you know it, it's 3:00 in the morning. That's how "World of Warcraft" goes.
There are so many different ways to play
There is no right or wrong way to play "World of Warcraft." You can grind out quests for hours on end in search of new upgrades and gear, you can do player-versus-player content forever or you can just go fishing for a while.
There are even special role-playing servers where players are expected to stay in character in the in-game chat. You could do that, if you're so inclined.
Having thousands of other players around makes it a truly social experience
I don't play anymore, but there was a genuine sense of community on my "World of Warcraft" server back in the day. The same group of knuckleheads would joke around with each other in the chat (much to everyone else's annoyance) every night, and I know people who married each other after meeting in the game.
Obviously, you can't get that in single-player games. It's fun to walk into one of the major cities as a low-level player and see all the veterans decked out in the most powerful gear, or to work with your friends to get through a challenging dungeon.