Way back at the start of 2011, we told you about a Sonic the Hedgehog 2 fan remake that was in the works. The appropriately named Sonic 2 HD is exactly what it sounds like: the classic Genesis game we all remember, updated with hi-res assets. It's not to be confused with Sonic Fan Remix, a similar project that completely overhauls the look of the original while threatening to be a little too busy. In contrast, Sonic 2 HD attempts to remain faithful to the source while adding a few extra nuggets here and there.
Over on the game's main page, you can download an alpha build that features all of Emerald Hill Zone but unfortunately no special stages. In static screens, it appears as though this HD "upgrade" had nothing more done to it than a simple filter application. On the contrary, not only have the characters been completely redrawn to better match the Japanese concept art, the animation quality is ridiculous! Just look at how smoothly Sonic and Tails pop into view during the title screen!
There are other little surprises tossed about, some of which you'll have to search high and low for. The most obvious one is the new level transition, which bridges Acts 1 and 2 à la Sonic 3. I hope there will be transitions between Zones as well in the final build!
Sonic 2 HD Alpha Release (Thanks, Jared!)