A really fun game, but there are a few bugs. The music was the biggest issue. I started the game and no music played during the Emerald Hill stage. I figured you just didn't add music, but when I got to Chemical Plant, the music started playing after I collected an extra life. I got to Aquatic Ruin and the music played like normal, but it muted after I struck an enemy. Confused, I restarted the game, but the music, unlike last time, played during Emerald Hill. However, when I struck an enemy, the music glitched, making some odd sounds, then muted.
Also, I like how you included enemies from the Sonic games into this, but one issue is that when powerups fall from blocks that hover over the platforms the ground enemies are on, I can't collect them. Lastly, maybe making the blocks you break something other than blue bricks would add some flavor to the game? Either way, it seems to be alright in every other regard aside from what I mentioned. Good job.