Sonic Generations is a blend of two games. The old school original Genesis 2D platformers that have you speeding through winding labyrinths. The other half has more modern Sonic games that are not only 2D platformers, but 3D platformers and straightaway running in 3D. After completing the first level as old school (classic) Sonic, you're treated to a story cut scene. The game then game opens up to the platforming hub level. The hub level lets you switch between the two versions of Sonic. Levels are full of loops, straightaways, platforms, rails to grind on, tubes to shoot down like Sonic 2's bonus round, spikes, death pits, water, red rings that will launch Sonic and many paths here and there. While Sonic can't swim, he just jumps higher underwater when he used to just move slow in previous games. The levels are throwbacks to previous Sonic games. Consider it a best of collection.
The game consists of three major chapters. Every chapter has 3 zones. Each zone has two levels (acts), the first level is that straight up 2D platformer and the second level is the more modern 3D version. You can tackle them in any order that you like. Once an act is complete, you rescue one of Sonic's many friends. After you complete the 6 levels of each chapter, then challenges become unlocked. Each zone has 5 challenges for each version of Sonic. 3 keys will also appear in each chapter and unlock when you complete one challenge from a zone. Then if you have 3 keys in one chapter, you can use them to unlock the boss for that chapter.
The challenges offer some variety with objectives. For the most part you're just running through the same levels you had to get through to unlock them. There are a few unique levels in the challenges. The challenges range from beat the clock, racing tails in a plane, racing your own doppelganger (ghost), timed drifts, enemies moving at double speed and completing a level with only one ring. Since you rescue Sonic's many friends, there are special levels that make use of them to help Sonic. Amy Rose has a hammer that if you time it correctly you can do a mega jump. Knuckles will dig up medals for levels that you need X number of medals to complete the challenge. Rogue will charm armored enemies so Sonic can defeat them. Every enemy that gets defeated in her level makes hollow blocks into solid ones. It feels like a way to make a 4 hour game into an 8 hour game.
Not only does every chapter have a boss, but there are also mini bosses. Basically you walk up to them in the hub level and challenge them. Once they're defeated, you get yourself a chaos emerald since there are no bonus levels like previous Sonic games. Each boss is original and unique, since Sonic has so many characters, you'll never fight the same one twice. The main bosses are gigantic. To take them down, its not just hitting a boss, but its timing the attacks when bosses are vulnerable and the way you'll need to make them vulnerable.
Since it is like two games in one, there are two sets of controls. The old school sonic that has just a jump button. Who can duck and hit the button to start a spin dash that he'll release when you let go of down. Then there's the modern sonic that has the same controls for the most part. Modern Sonic has a homing attack that will lock onto an enemy, springboard or claw and dart to them in mid air. This helps with traversing the land as its a lot quicker than loading up a spin dash. Sonic can now slide under objects as he runs, but it feels more like a quick time event than anything. There are even level specific controls like wall jumping back and forth. Sonic will even find a way to make him stick to walls and ceilings.
There is also a boost button that will send Sonic instantly dashing. The boost has a meter that decreases over time. To get boost you will need to collect rings. You can also get boost from drifting around corners when you're in a straightaway by holding the L or R when you go into turns. On top of that, you can gain boost by jumping through rainbow rings that will let you do mid air tricks by hitting the left thumbstick. Comparing the two control types feels like old school Sonic is one dimensional. This could be a subtle way of proving which character is better.
The Sonics also have skills that you can use to customize them. Things like stopping on a dime no matter how fast you're going. Getting an extra life when you run out. Not taking fall damage and so on. There are even skills just for classic Sonic and others just for modern Sonic. Each skill you unlock uses points. You have 100 points to assign the skills. So the better the skill, the less others you can assign. There are loadouts too for quick assigning.
As always rings are like Sonic's health. If you have a ring, Sonic can take a hit from an enemy or spikes. That will send the rings spraying from his body. If you don't have a ring when Sonic gets hit, he loses a life. The game's helper even announces it. The game's helper is a big help, especially with the challenges. The helper will explain everything as you play including how to defeat the bosses. You can of course turn the helper off.
Sonic Generations puts a real emphasis on speed more than the original Genesis games. The boosts, the loops, the bosses chasing you, a semmi truck trying to ram you, competing against doppelgangers. It all goes to prove that Sonic is fast if not parkour with his homing attack. At the end of each level and challenge, you get graded with par times. It almost feels like a racing game disguised as a platformer.
The game is beautiful, but it feels like a beast on my system, causing me to lower resolution. Every blade of grass gets rendered and everything is colorful. The only problem is Sonic is super small on the screen. He gets dwarfed by how gigantic the world is around him and the camera never really being tight up on him. As everything blurs from the speed its easy to lose sight of him in 2D. Because of this, some of the game felt to me like it was playing itself. Even the quick time slides still made Sonic slide when I failed to push a button. Not holding the thubstick still made him move. Some of it gets relegated to timing homing attacks to get over areas. Is that a bad thing? No its visually impressive even if I don't feel like I have complete control.
Another problem in the 3D worlds is no camera control. You're stuck looking at what the game wants you to. While that's not always a bad thing, it can be problematic. Sometimes I lost sight of Sonic or couldn't see a gap between areas sending into death pits. There were plenty of times in 3D terrain I jumped to my death. Often from misjudging where I was or from Sonic's slippery turnarounds. Often times Sonic would stop in mid air to fall to his death even having full momentum into a jump. Using boost to run over water is treacherous. Even in what looks like ankle deep water can send Sonic to his doom if you get clipped by a platform and stopped.
There are plenty of extras to unlock including artwork, music that you can select to replace the current level music. It is a lot of content with 18 levels, skills, 90 challenges. For me it felt like the fun didn't last as long as the challenge. The death pits and water deaths seemed too constant. Even with a few glitches here and there, the game is by no means bad. It is just trying to be everything at once. Playing the classic Sonic feels forced when modern Sonic has so much diversity. I'd rather play one or the other. To get to a destination, I can drive a car. Then I can flatten the tires and drive for 5 minutes. After that I can fill up the tires again. Then flatten the tires again after 10 minutes and fill up the tires again. I'll still get to my destination, but I'd rather not have flat tires from level to level. I would have appreciated if the game had two halves. If only you could complete a classic half and a modern half, without completing them both at the same time.