I doubt I'm blowing anyone's mind when I state the obvious, which is that MODERN SONIC IS FUCKING TERRIBLE. Besides the baby steps of growth shown in last year's Sonic Colours, Sonic continues to be a character with no place in the modern era. It's as if his supremacy as a platforming icon in the earlier parts of the 90s have lent him carte blanche to be shitty, over and over again, in new and innovative ways. Unlike Mario, which has grown and changed and evolved with the times (while still offering great classic platforming in abundance), Sonic continues to either blow out in spectacular ways (Sonic Unleashed, Sonic Tales series) or give us pale retreads of past glories (Sonic 4).
So when Sonic Generations promised to bring old and new together, the optimistic amongst us might have thought that perhaps this would be the chance that Sonic Team would take to fix some of the issues with modern Sonic and to finally, finally give the world a retro-modern Sonic game that felt right. Instead of that beautiful, Reese peanut butter cup-esque dream (and it always was a dream, let's be clear – even if you have a modicum of affection for Sonic Colours, feeling any sort of optimism for a Sonic game is inadvisable at best), we're left with something that is just… there.
And maybe that's enough for some people – Sonic has been so inexplicably bad and broken for so long that a game that is merely underwhelming is perhaps a godsend for long suffering fans. And to be fair as well, the 3DS version of Sonic Generations has a lot less to live up to than its HD counterparts, where opinion – especially on decidedly retro offerings – is incredibly unforgiving. The only thing that Sonic Generations had to do on 3DS was to provide Sonic Rush-esque thrills and be a competent game on what has been until very recently a struggling console. But in the context of this particular season, there are a ton of games, even on the 3DS, which deserve a person's time more than this game, and name recognition alone isn't enough to save Generations.
The first few minutes of the game, though, are totally awesome, and set expectations pretty high for the game. Once again beginning in the Green Hill Zone, Sonic Generations handily proves why Sonics 1 – 3 are some of the best platforming games of their generation, with twisty course maps, many routes to completion and breakneck speed tempered by actual player interaction. It might be a somewhat poorer recreation of past glories (the controls, while not as stiff as in Sonic 4, aren't nearly as fluid as they should be), but it's a million miles better than what happens next.
See, the hook for Sonic Generations is that chubby retro Sonic and lean modern Sonic have somehow met in a space-time continuum vortex of sorts, meaning that you play each stage twice (though they're slightly different in layout). Classic Sonic is great because it hits on the core of Sonic, something that has eluded Sonic Team for several (ahem) generations. But modern Sonic here isn't even really modern Sonic – he's just a shittier classic Sonic. Once again, having not played the console iterations of this game, I can't say for certain whether the 3D Sonic sections suck or not, but putting modern Sonic's repertoire of moves into a 2D-ish context simply does not work, mainly because his new actions strive to suck all of the joy out of controlling Sonic in the first place.
So basically what you're getting is two levels per world, one that is pretty good and one that is pretty bad, meaning that a full half of this game is essentially worthless. Getting flung from one end of a level to the other while hammering the boost or the "attack" button takes all of the player's agency out of the equation in the endless search for more speed, when speed was only ever one part of the Sonic equation. Worse yet, as the game goes on, modern Sonic's moves start infiltrating classic Sonic's levels, making them not only virtually indistinguishable but also BOTH BAD.
This isn't a New Super Mario Bros. situation, where Mario's 3D moves worked in the context of 2D due to a thoughtfulness of design – no, this is a hideous Frankenstein of game design where nothing ever fits together quite right. At the end of the day, you have a game that outwardly appears to be reverential of the classic games that should have inspired it – even drawing its levels from history in a particularly imaginationless way – but instead continues along the same trajectory that has hampered the Sonic series since the Dreamcast era. That makes Sonic Generations worse than simply the mediocre game it feels like most of the time: it makes it a disappointment, and one that stings all the harder for having the potential to not suck.