Sonic Adventure 1+2 HD Collection

Sonic Adventure 1+2 HD Collection (AKA, "Sonic Adventure 1+2") is a remaster collection of "Sonic Adventure DX: Director's Cut" and "Sonic Adventure 2: Battle" from the Sega Dreamcast, reworked from the ground up for current-gen platforms. Unlike the PlayStation 3 and Xbox 360 versions, which reused their Gamecube ports (albeit poorly), these remasters use new textures and models, realistic graphics, newly animated cutscenes, and restored content unused from their original ports.

OVERALL

 * Newly animated cutscenes and gameplay animations.
 * Newly recorded musical score.
 * Newly updated sound effects. (ex. Sonic's current jumping and ring sounds for "Sonic Adventure DX: Director's Cut")
 * By pressing "Retry" in the pause menu, you don't lose a life at all.
 * Better camera controls.
 * Both games' Chao Gardens can crossover with each others.
 * As a matter of fact, now there's a banking system for Chaos Drives and Animals you collect from both titles. They can be stored in case you ever want to feed your Chao a certain type, and make them the type of your choice between Swim, Fly, Run, or Power. You can even throw your Chao into the bank in case you don't want to accidentally give the wrong animal or drive to the wrong Chao in your garden.
 * If you give your Chao an animal, they can be reusable, whereas drives can't, unless you give it to your Chao from a slight distance (NOTE: This is based on the popular glitch).
 * The Chao Gardens themselves never looked better, with more open space for more Chaos to live in.
 * The Chao Black Market now sells regular Chao eggs you can get for 400 rings. They also sell Bronze, Silver, Gold, and Platinum eggs (and even the rare eggs from Dreamcast's online service) once you unlock them in "Sonic Adventure DX: Director's Cut".
 * The Chao Garden trees from seeds you plant can now never die down. In fact, instead of planting the seed right away, you can now direct the Chao to the spot you want.
 * Chaos now have unlimited incarnations. When you make them a Chaos Chao, they don't die and incarnate.
 * To make a Chaos Chao, don't worry as much. Just through your 2nd incarnated Chao into the storage for the drives and animals and press the new "Give Chao 1 of every animal feature", which only works if your Chao incarnated twice or more.
 * The Chaos' HUD now has a bar for happiness, intelligence, and alignment which were hidden in the original titles. Happiness is for if a Chao really loves you, and how happy you make it. Intelligence is for how many times you send it to school and make him/her smarter. Alignment is for if a Chao will evolve into a Hero Chao, a Dark Chao, or a Neutral Chao.
 * Chao Race and Chao Karate can now be played locally and online. Chao Race supports up to 4 players locally, and 8 players online.

SONIC ADVENTURE DX: DIRECTOR'S CUT HD

 * A brand new multiplayer mode for 2-4 players. You can basically play the characters' stages in split-screen multiplayer action.
 * You can even play as the characters from "Sonic Adventure 2: Battle" in just the multiplayer modes alone. Tikal is even playable, with the same gliding, digging, and wall-climbing abilities she had in "Sonic Adventure 2: Battle".
 * Dr. Eggman is playable too in the multiplayer mode.
 * Tails can fly indefinitely in the Hub worlds, but still has limited flight in levels.
 * No fall sound effect is used when the characters shoot out of a cannon, along other areas of the game that used it on the older versions.
 * When you play in the hub worlds as Sonic, Tails, Knuckles, Amy, E-102, or Big, you will now have a mini-map to guide you if you ever feel lost. The mini-map also gives you the location of shiny eggs, hidden power-up upgrades for certain characters, side quests, and other secrets.
 * The hub worlds are now more bigger and spacious than the original version, allowing for more open-world exploration.
 * The loading screens are long gone.
 * Better fishing controls for Big's levels.
 * Super Sonic now has full flight mode, altering the final boss of the game just a tad.

SONIC ADVENTURE 2: BATTLE HD

 * Like the GameCube port, all the characters and stages in the 2-player mode are unlocked from the start.
 * Non-story characters like Amy, Tikal, Metal Sonic, and Chaos are only playable in the Chao Gardens.