Here are the new features outlined on the official website:
■ Modes Overview
Sonic the Hedgehog 2
The standard mode. Start playing from three different game types. The Sega Ages version also allows you to use the “drop dash” action added in Sonic Mania. Additionally, a window has been added to display your “Ring Chain,” the amount of rings you pick up without getting hit, and your “Max Ring Chain,” your greatest amount during that play session. Two-player co-op is also supported.
The additional elements that are not in the Mega Drive version can be turned off in the Option settings.
—01. Original Mode
A faithful reproduction of the Mega Drive version.
—02. Ring Keep Mode
A beginners mode in which you can enjoy a more casual Sonic the Hedgehog 2. You start the game with 10 rings and lose only half the amount of rings when damaged.
—03. Super Sonic Mode
A special mode in which you play as Super Sonic. This will be unlocked by clearing either Original Mode or Ring Keep Mode. Super Sonic Mode lets you play with possession of all the Chaos Emeralds and 50 rings from the beginning of the game. By jumping when you have 50 or more rings, you will transform into Super Sonic, who has overwhelming speed and strength.
Knuckles in Sonic the Hedgehog 2
A mode that reproduces the special mode originally only playable by locking-on the Sonic the Hedgehog 2 cartridge to the Sonic & Knuckles cartridge on Mega Drive. This allows you to play every stage of Sonic the Hedgehog 2 as Knuckles. By using Knuckle’s glide ability, you can reach places Sonic and Tails cannot, and maybe even discover some new secrets. Just like Sonic the Hedgehog 2, this mode offers three modes: Original Mode, Ring Keep Mode, and Super Knuckles Mode. (Super Knuckles Mode can be unlocked by clearing Original Mode or Ring Keep Mode using Knuckles.)
A Sega Ages-original mode where you compete against the time to collect 100 rings to make it to the goal. You can play as either Sonic or Knuckles.
Sega Ages Sonic the Hedgehog 2 also features online rankings. “Ring Chain Ranking,” which was well received in Sega Ages Sonic the Hedgehog, now allows you to see replays. There are also Challenge Mode rankings for both Sonic and Knuckles.
Sega Ages-Original Elements
In addition to being able to switch between the Japanese and western versions of the game, you can also turn on the Stage Select feature previously accessible through a cheat code. You can also enable “Vintage” picture mode, which emulates the image produced by a CRT TV. There HD Rumble support, which creates comfortable vibrations whenever Sonic does a spin dash, jumps off a spring, destroys an item box, and so on.
View the screenshots at the gallery.