My first serious hack! I used lunar magic, yy-chr and Romi's Addmusic.
It is a little short, it has only 6 levels. The best ones are "Bobomb Land" (2D version of Bobomb's Battlefield), Retro 1-2 (The classic 2nd Level of SMB1 in 16-bit) and "Sonic WTF" (I tried recreating the first level of sonic 1 with mario world objects)
This is not a proper screenshot. Screenshots that are accepted are 256x224. Just set that option in your emulator. Also, you might want to take more than just one screenshot. That would be beneficial for the people who want to see what your hack looks like, and could be beneficial for you to get more people to play.