Sonic 4's second episode is better than the first, but it's still got a ways to go
The game takes place almost immediately after Episode I. The Egg Station may be destroyed but Dr. Eggman still has a few tricks up his sleeve. After reviving one of Sonic's oldest enemies, Metal Sonic, he plans on creating a brand new Death Egg (aka the Death Egg mk 2) around Little Planet from Sonic CD. Sonic, now with Tails by his side once more, sets off again to foil Eggman's new scheme.....again. The story is as basic as it gets like the old games but it is nice to finally see Sonic CD get tied into the timeline as well as Sonic 3 & Knuckles.
Once again, the game is in a 2D sidescrolling perspective, but it doesn't play much like the classics. The biggest difference between this and Episode I is Tails is now included as a secondary character, but he can't be played alone. He doesn't help a whole lot, much like the classic games, but he is used for flying you across pits or to higher locations or for doing an even more powerful roll to get through certain obstacles. Tails adds to the gameplay and makes him more useful than he was in the days of the Genesis. Also, co-op has returned and is even a little better than the old games. Tails feels more important in co-op as him dying can cost you a life and you practically need the second player to help you through the game. Like I said, the co-op is more fleshed out but there's still the matter of outrunning the other player which forces him to be pulled back on screen. The Wing Fortress zone act 1 is the best use of co-op though, where one player controls a plane while the other person has to stay on the wing and attack enemies.
Other than that, it plays a lot more like Episode I, but there are several improvements. First off, the physics are better. They're not classic, but they aren't nearly as floaty as the first game, you don't stop dead in mid air when letting go of the stick or d-pad, you can't walk up the side of a hill (well, you kind of can but not as easily) and there is at least some momentum taking place within the level design. Secondly, the levels and bosses are better. Much like the first game, they reused themes from the old Sonic games but they feel much more original in their aesthetics this time like combining a snow level with a carnival level, or crossing Oil Ocean with a desert level. Sylvannia Castle and Sky Fortress feel too familiar but none of the levels feel as rehashed as the first Episode. Even less rehashed are the bosses, which are all 100% original this time and they all play much better too. So this game has a few untouched issues and it has a ways to go before the game earns the title of "Sonic the Hedgehog 4" but for the most part, the game is a solid improvement.
The special stages are back too, of course. Kind of like how Episode I reimagined the Sonic 1 special stages, these are more like the Sonic 2 special stages; running down a half pipe while trying to collect a certain amount of rings before each checkpoint. It's an interesting remake and Tails doesn't screw you up nearly as bad as he did back in Sonic 2, but not a whole lot has changed here besides tethers (Sonic and Tails are tied together and you can swing Tails around obstacles to your advantage) and timed sections (collect X rings in a section to earn extra rings). Super Sonic makes a return as a playable character once all emeralds are collected.
The graphics are better too. Instead of the more cell shaded look of the first, we see a more 3 dimensional look with more details levels and busy backgrounds. The graphics look great and bring each stage to life. The music, on the other hand, is not much of an improvement. Overall, there are more tunes I liked in this game, but they still try way too hard to recreate the Genesis sound and it just comes out as annoying and ear splitting (although, once again, not as bad as before).
In the end, Sonic the Hedgehog 4 Episode II is a lot better than Episode I, but it still has a way to go before it can be considered a true sequel to the Genesis titles. The physics and gameplay feel much better this time and the extra additions like Tails are welcome and make the game more interesting. However, it still falls short in music or just successfully capturing the feel of a Genesis Sonic game. They're so close, and I wish to see Episode III be made so we can make even more improvements and hopefully we'll eventually get the retro Sonic game we all wanted.