The background is certainly interesting. The colors on those rocks with what I'm guessing is moss/foliage in the back are inviting, I'm seeing some red come through on the green parts. I don't like how the gradient goes straight to black on the yellow rock structures, I would have made the yellow go into orange, into brown, and then into black. The clouds make the background more dynamic after seeing so many horizontal and vertical, orderly structures and features. I wonder why the foreground tile colors are still so garish. Maybe it's a WIP, I don't know, but something should be done about that. Overall, my main nitpick is that the way the whole background is rendered comes off as sterile. There needs to be more depth as to how backgrounds are colored, I want there to be hints of certain colors in spots and interesting hues peeking through the base color so you get the idea that it's not all made of plastic. As far as the characters go, Sonic and Robotnik look appealing as the rendering looks to be subtle. At the same time, I'm concerned that when Sonic is really moving, it might be hard to distinguish him from the background, since this picture suggests that everything is rendered in similar way. Tails could look a little more alert, maybe make his eyes a little bigger and have his pupils touching the top of his eyes like Sonic's do. That's all I've got to say on this since that's all I've seen. I do wonder about the programming aspect of it though, and the actual goal in making this game. I don't want to say this is like Sonic 2 reimagined, but those concept tiles look similar to Emerald Hill's, and there's the Death Egg back there. Yeah, I hope that the artist being as competent as he is that he does not do a re-imagining of any of the classic games, but to do something entirely different.