With a variety of content and a decently lengthy story, Sonic Adventure is one platformer that shouldn't be missed.
The plot is that Doctor Robotnik (Eggman) has given up on his inventions, and somehow gets into control of a watery god of destruction named Chaos. Every time Chaos is given a chaos emerald, it becomes more powerful, and since it's a creature with godlike powers, it cannot be killed by any efforts of Sonic and his friends, and therefore must beat them to the chaos emeralds before Eggman or Chaos gets to them. Other than Sonic and Tails, there are also other parts of the plots the player can play to further understand it. Knuckles must get the pieces of the Master Emerald back before Angel Island sinks into the ocean since Chaos destroyed it, Amy has problems of her own by being chased by a robot made by Robotnik to capture a bird that Eggman has interest in, newcomer Big the Cat looks for his friend Froggy after he wanders off into potential trouble, and E-102 Gamma must obey orders from Eggman until a conflict happens where he is unable to any longer.
The game is broken into three portions: The hub world, Action Stages, and Mini Games.
The hub world turns into multiple things throughout the game. The hub world will become night during certain parts of each character's story, and is broken into three different locations. The action stages are the core stages, and differ between every character that is playable. Sonic must traditionally complete the stage, Tails needs to beat Sonic to the end of the stage, Knuckles must get three pieces of the Master Emerald, Amy needs to escape from the robot that is chasing her, Big has to catch Froggy in the bodies of water, and E-102 offers shooting stages where the objectives frequently differ.
There are multiple mini games or "sub-games" as the game refers to them, with multiple objectives. While there are only three, two being an on-rail flying game and the other being a snowboarding/sandboarding game that comes as Sonic and Tails.
For a game that was released in 1999, the game looks fantastic. Textures are smooth; the character models look good, as well as the settings. It's debatable that graphically the game kind of acted like a tech demo, as the whole reason Chaos is made out of water was because the team wanted something that would be hard to render, something that cannot be done on any other home platform. This is probably the most visible in the intro sequence.
The game altogether plays great. The controls are precise and much of the game feels like it was put together with good effort. Sonic is easily the fastest character followed by Tails (who is capable of flying however), Knuckles can climb on the walls of the stages as well as gliding, Amy runs slowly (while tedious, understandable) while she has a hammer as a weapon, Big the cat also goes slowly, but the fishing controls at least somewhat decent, and Gamma is a lot of fun to play as since it's more of a shooting based game.
The music in the game tends to is quite fitting for the stages and helps give more of an atmosphere to the game. With one of the more memorable tracks (to me at least) being Emerald Coast.
This happens to be one of the first (if not the first) game in the Sonic the Hedgehog franchise to fully adopt voice acting, and it actually isn't half bad. While it's sometimes exaggerated and cheesy, this eventually sets the slate for voice overs for the future of the franchise. It improved greatly around Sonic Adventure 2, but I suppose that is a story for another day.
Sonic Adventure does have quite a bit to offer when it comes to replay value. Once you finish the main story, the primary goal is to collect all of the emblems by completing all of the other action stages in order to achieve one-hundred percent completion of the game. Some of the emblems are a total joke (like getting most if not ALL of Tails') while some can be difficult (like the Knuckles stages which can occasionally be heavily reliant on your luck), while some others can be flat out tedious (Big, where you need to catch more fish before catching Froggy.)
For flaws of the game, in all seriousness I only have two.
The first problem I've had with the game is the occasionally very picky camera. Sometimes it decides to have a mind of its own, and decide to look the way you don't want to and cause you to fall to your death in some cases. This can get really annoying, especially if this happens on the Casinopolis stage as Sonic (which I've only had happen once though.)
The other problem I have is all of the action stages that Big has. While I do enjoy the diversity Sega and Sonic Team decided to add with putting Big in as a playable character, his stages just get so tedious and boring to play not too long after you begin playing them. Especially Ice Cap and Emerald Coast are really bad as you need to go throughout the entire stage on multiple occasions just to get an idea on where Froggy is and how you can potentially catch him. It's just so tedious, and I don't know anyone who played this game just to play as Big.
In the end, Sonic Adventure for the Dreamcast was a huge feat for its time. Just seeing it compared to what the Dreamcast's competitors had to offer at the time made everything just look like a total joke. It takes platforming and brings it to a new approach. Sonic fans that have somehow yet to experience the game should try picking it up, or at least get one of the re-releases, along with any other person who enjoys platformers. If you're not too big on 3D Sonic games as a whole though, this won't change much, but is at least worth a look.
Presentation – 8.5
Graphics – 9.5
Gameplay – 8
Sound – 8.5
Replay Value – 8.5
Overall – 8.6/10 (8.5 rounded to the nearest decimal)