If you are a fan of Sonic, you should totally check out this game. It is primarily being made by a guy named “pelikan13,” who has been working on it for some unknown period of time. He just released a demo of the game today, which you can download right from the main site or using torrents from a mirror site (much faster).
The demo is very impressive, to say the least. Maybe I am crazy but it just feels more like what a Sonic game should be than Sonic 4 is. My biggest concern at this point, would be that the game almost looks too good and detailed, but I generally really like the visual style.