Sega chose Green Hill zone to showcase Sonic Generations in its first trailer.

It was an easy and obvious choice. With its grassy emerald slopes, rock-carved loop-de-loops, and lush vegetation, this iconic level is almost as recognizable to the series as Sonic himself. Those fans that have continued to stick with Sega's oft-beleaguered mascot know (probably better than most) just how much of a punch nostalgia can really pack -- and how painful it can be when a character's guardians won't stop tinkering with a beloved property. Needless to say, the wounds of past mistakes made watching the re-appearance of classically styled "fat" Sonic running through a modernized, 2.5D Green Hill, a metric most fans had given up on ever properly seeing, an even more affecting sight.

Generations seems to finally be the apology, more or less, that Sonic fans have been waiting for Sega to make for years. Birthday present or not -- 2011 marks 20 years since Sonic made his original Genesis debut -- Generations is also potentially the series' most interesting entry. With old and new gameplay styles literally butting heads, Sega has put themselves in a unique position with no clear future.

I mentioned this to Generations' producers at this year's E3, asking if Sega had considered how re-introducing fat Sonic and his classic mode of gameplay was somewhat akin to painting themselves into a corner. "You can't just put classic Sonic back in the vault now," I said. "The fans won't stand for it." Though they told me the spirit of classic Sonic gameplay will be kept in mind for future projects, I wonder how much, if any, the game's sales may change their tune. For Sonic fans, Generations is nostalgia.

The whole premise stems from memories. Moving through a platforming hub made up of different points in time (read: levels) from throughout the series, old and new Sonic have to team up to rescue their friends from being trapped in limbo by a space-time eating monster. It's a clever way to justify different gameplay styles, and to see modernized iterations of fan favorite levels like the aforementioned Green Hill or Chemical Plant, not to mention retrofitted or retooled versions of levels from newer (or older) games. But where's the Casino Night stage?

Thankfully, 2D levels have nevertheless been completely re-done from the wonky physics seen in Sonic 4. Gone are the lock-on attack and maddeningly strange lack of momentum -- fat Sonic's movement perfectly captures the fluid essence, sense of speed and multiple path design of his Genesis outings. As far as throwback gameplay is concerned, this is sublime, and that's really all you need to know. Modern Sonic also fares surprisingly well, with 3D stages optimized for blistering speed (occasionally to the game's detriment, even). Sega has mostly fixed the issues past games have had with dimensional perspective, and these amusement park-esque, on-rails-ish sequences actually provide a bombastic contrast to the down-to-earth 2D sections. The polish in both styles is evident.

Is Generations the perfect Sonic game? No. But it's a great step in the right direction, even over last year's impressive Colors. Some weird design decisions, like forcing you to play through a certain number of optional challenge levels in order to unlock boss battles, can disingenuously make progression feel a little off-kilter at times. At the same time, certain characters are limited to a single encounter. You and I may not care much about seeing Shadow, but just one match against Metal Sonic is disappointing.

On the 3D front, you'll still occasionally have lock-on issues or suffer confused, unavoidable deaths from the breakneck pace, and it can at times be pretty jarring to switch back and forth between classic and modern gameplay styles. (Also, Sega, Super Sonic needs to be patched. Right away.) Still, for a tribute to Sonic's history, Generations is great. Perhaps now Sega may finally realize the truth about fat Sonic: he's been the answer to their problems all along.