Still the best 3D Sonic title to date, and possibly one of the best 3D platformers of all time.
The story is pretty much what it always is; Dr. Eggman is on a mission to gather all seven Chaos Emeralds and rule the world, and once again Sonic and friends must stop him from succeeding, but now there's the added danger of Eggman's new ally, Chaos. Chaos is a mysterious entity made of water, and when he absorbs the Chaos Emeralds, he mutates into many hideous forms that become more and more powerful. The game itself has six different story modes, all with a different character and style of gameplay. Sonic has the longest story with 10 stages, all of which revolve around speeding through courses to reach the goal; Tails' levels let you play the two-tailed fox in stages similar to Sonic's, but this time you need to keep up with Sonic and beat him to the finish. Knuckles offers a treasure hunt game, here you need to help Knuckles retrieve shards of the Master Emerald that Chaos shattered and restore it to its original form; Amy Rose has the shortest story (only 3 stages) and she has to escape capture from Eggman's henchmen in order to beat the game. The two newcomers, Big the Cat and E-102 Gamma offer very unique levels, Big's story revolves around fishing, and Gamma's story combines running through levels with a shoot 'em up flavor to them.
The gameplay itself is pretty solid, but I doubt that aside from Sonic and Tails levels, they have little lasting appeal. While Knuckles' treasure hunt levels can be fun, after a while they become tedious and repetitive. Amy's slow speed and brief adventure do not make a very exciting campaign for her, and you won't find anyone playing these stages for fun anytime soon. The adventure field itself was a nice addition, but it became a chore to locate some of the levels and I found myself wasting a fair amount of time finding them, a mission mode would have been nice too (one was later added to the Gamecube port). The coolest feature has to be the Chao, they were introduced as an A-life system in which the player can raise these little creatures and race them, you can even take your Chao and load it into your VMU for a virtual pet adventure game.
While the control is great, the camera can lead to problems and in some cases an untimely death; this has been a constant problem in 3D Sonic titles, and leads me to question why Sonic Team can never seem to get it right. Even though the US version fixed many glitches and bugs from the Japanese game, there are still a few bugs apparent here, a common one I see is Sonic falling through solid floors in the adventure field in some areas, but it's not a huge factor. Even though this game is over 7 years old, it is still a beautiful game graphically; even as the years go by, every time I pick up this game I am impressed by the eye candy it can deliver. The game also delivers a great soundtrack, Sonic games have always been known for superb music tracks and this one is no exception (you should especially check out Open Your Heart and Sonic's theme, It Doesn't Matter.)
All in all, it's clear to see how this became the Dreamcast's top-selling title, and one of Sonic the Hedgehog's top-selling games to date. It offers a fresh take on the platforming genre and gives a variety of gameplay styles that any player should become accustomed to. Whether you like Sonic's speed, Knuckles' search and rescue, or even Big's fishing prowess; Sonic Adventure will give you many hours of enjoyment and is definitely a must have for Sega's final console.