Sonic the Hedgehog 4 Episode 1 takes a trip down memory lane to revisit locations and bosses from Sonic's past with new level layouts and a few other new tricks here and there. Splash Hill Zone and the Lost Labyrinth Zone are a dead ringer for Sonic 1's Green Hill and Labyrinth zones, while the Casino Street Zone and Mad Gear Zone represent Sonic 2's Casino Night and Metropolis zones. Unlike previous Sonic games, there isn't a set order to the levels, with the ability to jump straight to act 1, 2, or 3 of any zone unlocked once you've beaten the first level. It's a nice way of opening up the game for portable play so that you can pull out your iPhone for a quick level here and there without needing to constantly replay the first few levels. Though it would have been nice if there were still an option to play the whole game through in sequence, since it can get irritating quitting to the menu after every single level. Once all of the acts in a zone are completed, you can face off in a boss battle against Dr. Robotnik using modified versions of past Sonic 1 and 2 bosses.

The levels themselves are a mixed bag. Some, like the entire first zone and the first act of the other zones, are definitely on par or surpass some of the classic Sonic levels from the Genesis games. The balance between speed and precision platforming is pretty much perfect, with multiple routes for those willing to explore or who have the skills to reach them. Others, like Casino Street's second act and the third act of the Lost Labyrinth and Mad Gear stages, deserve to get thrown in a pit, shot, set on fire, shot again, and never spoken of again. Remember that horrible bit in Sonic 3 (Hydrocity zone, act 2 to be exact) where a wall was threatening to crush you for a part of the level? Well Sonic 4 has two entire levels of that, and they are horrible. Why a level designer would recycle one of the worst parts of the Genesis games, and expand it to two entire levels, is a complete mystery to me.

There are two levels exclusive to the iPhone, set as the second acts of the Lost Labyrinth and Casino Street zones. The exclusive Lost Labyrinth level uses the infamous minecart that was leaked much to fan outcry, and is actually one of the best levels in the game. It's amazing how much difference a few months can make. The exclusive Casino Street level on the other hand is a pinball level consisting of a single slot machine in which you must amass 10,000 points, and is just as dull and monotonous as it sounds. On the whole the good levels outweigh the bad, but the bad ones really bring down the experience.

You have two options for controlling Sonic on the iPhone, virtual d-pad or tilt controls. Virtual d-pads are always tricky on the iPhone, with the one used in Sega's Genesis iPhone ports being particularly finicky, so I was pleasantly surprised by how well it worked in Sonic 4. Ducking, which is essential for spin-dashes, still gave me a hard time on occasion, and there were times when my thumb wandered from the small jump button at inopportune moments, but I must say that the touch controls in Sonic 4 are among the best I've seen in an iPhone platformer. It's certainly no replacement for a physical d-pad, but Sega did an admirable job with what they were given. Of course, this was only feasible for me because I have relatively small hands that didn't cover up much of the screen. Players with larger thumbs will likely cover a large portion of the bottom corners of the screen which can be especially problematic during boss battles when hazards come from those directions. For those with well-endowed digits, Sonic 4 also supports tilt controls, which I wasn't really fond of. The tilt controls feel slower, and made it much more difficult to pull off quick turns both in the air and on the ground. Though there were two exceptions where tilt controls seemed a perfect fit: in the special stages that borrowed the style of Sonic 1's special stages and the minecart level. Underwater levels also work fairly well with tilt controls, since Sonic's slower underwater speed matches the pace of tilting.

There has been some controversy over how Sonic controls this time around. A homing attack was added for the first time in a 2D Sonic game. This was followed by the discovery that Sonic, when launched into the air from a ramp or spring, would not be curled into a ball to attack enemies. I mention these changes together because they actually compliment each other quite well. While the iPhone touch controls are decent, they are by no means perfect, so precisely landing on enemies isn't always feasible. The homing attack is a great solution to this issue in iPhone controls, allowing Sonic to hop from enemy to enemy without needing to quickly tilt your device or mess with a virtual d-pad. As for Sonic not curling into a ball when launched in the air, this becomes a non-issue since the iPhone controls essentially dictate the use of the homing attack most of the time. Sonic purists may still cry foul, but at least in the iPhone version it is an understandable and necessary concession. With limited control options, tapping the screen to attack an enemy works far better than trying to control Sonic to land on their heads.

There are plenty of extras thrown in for replay value. All of the levels can be played in their default Score Attack mode, or switched to Time Trail mode to allow you to post your best speed runs on the game's global leaderboards. There are also seven chaos emeralds to collect in the game's special stages, which can also be replayed in Time Trial mode and are by far some of the more challenging parts of the game. Finally, completing all of the levels and boss battles will unlock a final, ridiculously hard level. I won't spoil it for you, but longtime Sonic fans will certainly enjoy it, even if their nostalgic smiles are through gritted teeth from the difficulty.

For those worried about the title's "Episode 1" meaning a shorter game, I have good news and bad news. The good news is that Sonic 4's length is on par with past Sonic games. the bad news is that it's on par with Sonic 3 and Sonic & Knuckles rather than the much longer Sonic 1 or 2. Including the final level, there are 13 acts total. And though it may have the same number of levels as Sonic 3 or Sonic & Knuckles, the game actually feels shorter because the levels are spread across fewer zones giving you less visual variety. Considering the game's premium pricing, I had hoped for a little bit more. But also keep in mind that price could move all over the place during temporary sales given the precedent Sega set with the rest of its iPhone gaming library.

Special mention should also be given to the game's presentation. The 3D character models perfectly recreate their 2D sprite counterparts, right down to the random animals that pop out when an enemy is defeated. The levels are also gorgeous, with multiple foreground and background layers at work to give Sonic's world a much richer look than it has ever had in 2D. There are a few levels that appear dark on the iPhone's glossy screen if you are playing in a very well-lit area, but the overall look is spectacular. The soundtrack also deserves special mention. The Genesis Sonic games rank among my favorite videogame soundtracks of all time, and Sonic 4 recaptures the feel of those tracks perfectly.

Sonic 4 is worthy of its title, and makes the transition to touch controls relatively intact. Even with changes like the homing attack, Sonic 4 still feels unmistakably like a Sonic game from start to finish. It's by no means perfect, with a few bad levels and imprecise touch controls that plague almost all iPhone platformers. But if you don't own a Wii, PS3, or Xbox 360, then Sonic the Hedgehog 4 Episode 1 on iPhone will certainly be a welcome homecoming for Sonic fans.