Guild Wars 2: Changing the Game

Calling it "one of the most impressive MMOs in development", IGN backs up that claim with a detailed preview that covers the game's skill system, quest system, Engineer profession, underwater combat, and more. A taste:
Skill collection factored heavily into the original Guild Wars experience. Gear had statistical bonuses, but wasn't as essential as armor in, say, World of Warcraft, where the proper gear is required for success. Leveling was deemphasized, and even though the level cap in Guild Wars 2 is 80, leveling isn't meant to be the main focus. It's more a gauge of progress, like watching an odometer tick up on a road trip. Instead, the prime motivation for playing was to collect skills. ArenaNet likes to compare their way of doing things to be more like Magic: The Gathering than Dungeons & Dragons. Your skill set is your deck. Even after collecting what's best, you still need to learn how to use it all properly.

The key to the skill system in the original was that every skill couldn't be active at once. You had to pick which worked best together. Guild Wars 2 builds on this concept. Predefined skill sets are tied to weapons. If an Engineer equips a two-handed rifle, then the same skills will always be active across one half of the skill bar. Assuming the skills are unlocked, you'll get an overcharge shot to knock back enemies, a net shot and a jump shot every time. Drop the rifle for a one-handed pistol and shield and a new skill set opens up. The locked skill set associated with each weapon functions as an equalizer. If you see a player using a particular weapon type, you know they have these base skills. For customization, there's the other half of the skill bar to play with.

For the Engineer, this means swapping out kits. There's a mine kit, a flamethrower kit, a grenade kit and more. When activated, the kits replace the five weapon skills with a unique set. So if you activate the grenade kit, you can toss out poison grenades, freezing grenades and fragmentation grenades for as long as it makes sense. When you're done, you can then quickly drop the kit skills and return to your basic pistol or rifle set. The same goes for the flamethrower, letting you blast out fiery jets to singe multiple targets or set up a firewall along the ground to do damage over time to any immobile opponents.