Planescape: Torment. Baldur’s Gate. Icewind Dale. Neverwinter Nights.

Each of these games is a link in a long chain of popular Dungeons & Dragons-based CRPGs (or “computer role-playing games,“ for the uninitiated). If you’re not familiar with the D&D genre, the premise is fairly straightforward. You start out by creating your main character, like an elven wizard or a dwarven fighter. Then you are immediately immersed in the fantasy world of the Forgotten Realms, where your character has all sorts of extraordinary adventures.

The latest iteration of this genre, Neverwinter Nights 2, came out in Fall 2006. At first, this game didn’t seem all that different from its many predecessors — the same character creation, the same great fantasy adventures, just with better graphics. Then in 2007, came Mask of the Betrayer, NWN2’s first expansion, which added a new superbly-written plot, and several cool new features. While it was a superior expansion, Mask of the Betrayer wasn’t exactly innovative.

But that’s all about to change.

Obsidian Entertainment, the developer of Neverwinter Nights 2, has announced that they are producing a second expansion, Storm of Zehir. So, another fantasy adventure, a few more cool little features… no big deal, right?

Wrong. The folks over at Obsidian are working on a few new features for Storm of Zehir that could potentially revolutionize the genre.

First of all, they’re changing the world map. Now that doesn’t sound particularly special, so allow me to elaborate. In previous D&D RPGs, if you wanted to travel to the dragon’s cave, or the mysterious tower, all you had to do was click on a little picture of your destination on the map, and your little party of adventurers would arrive there instantaneously.

But now, the old-fashioned 2D map has been replaced with what the developers are calling the “overland map.” What’s the difference? Well, the overland map is in 3D, for one thing, but more importantly, it’s a persistent world. That means that when your party walks out of the gates of the city of Neverwinter, you’re standing right outside the city on the overland map, rather than taken to the magic map to choose your destination. So now, if you want to get to that dragon’s cave on the other side of the world, you have to walk there, and experience everything in the game world along the way. So you could discover a traveling caravan, or get ambushed by savage orcs.

What’s more, your character’s stats will affect what happens in the overland world. So if your character has developed a good “Spot” skill, you might spot the hidden entrance of a lost dungeon. Or if you’re skilled at “Survival,” you might just be able to evade that horde of ravenous zombies chasing you.

The new overland map makes for exciting, non-linear gameplay like never before.

But wait, there’s more!

In Storm of Zehir, you don’t just create one main hero; you create an entire party of adventurers. “That’s not a new feature!” yell the fans of Icewind Dale. It’s true, you did get to create a full party in ID and ID2. However, in those games, your additional party members were just mute clones who swung their swords and cast their spells while your main character did all the talking. In SoZ, any member of your custom party can contribute to character interaction at any given time. So your evil rogue might demand a helpless traveler’s money, only to get smacked upside the head by your lawful paladin.

“But what about joinable companions?!” cry fans of Baldur’s Gate. In BG and BG2, as well as the original NWN2 campaign, you generally did not create more than one main character (outside multiplayer); instead, your protagonist was joined by numerous eccentric and interesting companions who formed your party. These companion characters were created by the developers to have complicated personalities, multiple interactions with your own character and each other, and even romances. Well never fear, companion fans, you have not been forgotten either. In addition to your user-created characters, your party can be joined by developer-created cohorts, complete with the same eccentric personalities and secret agendas.

This combination of highly-customizable companions and pre-made cohorts in Storm of Zehir is easily the most customizable party creation system in any D&D CRPG to date.

Add on top of all of this a gripping new storyline, several new character classes and races, new spells, feats, monsters, updates to the engine and graphics, a new soundtrack performed by a live orchestra and you’ve almost got a brand-new game, not just another expansion pack.

But don’t just take my word for it. You can watch Obsidian’s Matthew Rorie demonstrate the new overland map and party system over at Gametrailers.

Storm of Zehir is scheduled to be released this fall.