Not the best, but a pretty good successor
Ever since I came to Newgrounds, I had enjoyed the original Sonic Boom Cannon and later on found the sequel to be so much fun with the expanded content. Now you bring us a brand new Boom Cannon and decide to take the 3D approach. It was a interesting concept, but the constant turning eventually gets really boring and unamusing, leaving you with nothing more than the same game as usual that "turned" every now and then. I was also disappointed that there weren't many Mini-Games aside from the secret ending, which wasn't as fun as the other minigames in Boom Cannon 2, nor was it all that challenging; felt more like mashing the z button and the arrow keys than an actual fight.
However, as opposed to some of the others here, I actually appreciate the reduction of characters in the roster. With the exception of Super Sonic being absent from the list this time, I'm pretty happy with the selection made. The brand new power-ups you made were also well created and added a new, fun gimmick to the Boom Cannon series (only the 'Free Turn' went by unused for the most part, mostly me not caring for the 3D gameplay). You returned the use of the shields in this game, which was very welcoming. And the removal of the daily shop in favor of an all accessible shop was much more appreciated. I also like how you implemented a time gimmick into the game by determining the time of the level and the character used for the final fight by the use of the clock.
So basically, it's a game that takes the same formula as before and attempts something different. While in my opinion it doesn't succeed at what it tried to do, it's still a great cannon launch game in its own right. Props to you. If for some reason you do decide to make another cannon game (Sonic based or not), stick to the 2D or find a way to make it so you can angle your shots and bounce off of walls.
My highest score at the time of this post was 92964 using the Wechidna (the glitch Knuckles from Knuckles Chaotix)