This game is a frankenstein abomination of different Sonic games and really has no business being called Sonic 4. If you're looking for a good Sonic game to play or a new 2D platformer, skip this one and head straight for Episode 2. That
is a much better game. If you're looking for a good nostalgia trip, grab Sonic Generations. If you're still on the fence about this one, read on.
Sonic 4 Episode 1 is the first part of an episodic approach to returning to Sonic the Hedgehog's roots, riding the 2D revival bandwagon started by games like New Super Mario Bros. There is nothing wrong with the idea, but Sega put absolutely no effort into preserving their most important mascot's heritage. Sonic 4 was outsourced to Dimps, which makes its complete failure even more baffling, as Dimps has made several decent to good handheld Sonic games over the years. They must have let the janitorial staff take over for this project, because it's clear no one understood what makes a good game, let alone a good Sonic game.
The graphics are garish with a prerendered art style that isn't evocative of any Sonic game except maybe 3D Blast (which no one wanted to be reminded of). The music sounds like it's coming out of a bootleg Genesis/Megadrive; the compositions aren't necessarily bad, but the sound is very unappealing. The level design is bottom-tier Sonic but still modeled after actual Sonic games, but the borked physics result in bizarre situations like Sonic moonwalking in slowmotion on a ceiling, or just stopping on a dime.
For a game called Sonic 4, it takes several steps back and uses its predecessors as crutches. As such, its truncated level selection gives us such wonderful, original zones as Emerald
Splash Hill Zone, Casino Night
Street Zone, Lost
Labyrinth Zone, Metropolis
Mad Gear Zone, and Death
EGG Station Zone. So to sum it up, we have an inferior rehash with half the content of a typical Sonic game due to its episodic nature. Someone at Sega must have wised up because Episode 2 is such a big step up over this and I can't recommend someone put up with it when you can get far better Sonic experiences on Steam.