Overall amazing game! I do have an idea! When the clock his zero, what if instead of dieing, you lose your powerup, and you have until the invincibility frames go to hit an enemy! If you can't hit one, then to small mario, then death! it would be a great way to increase value of coins and to make the player feel like they clutched. If you do add this, adding a 5-10 second cooldown to the roulette would balance this.
Again, this game is awesome already, and it would be an awesome time waster if you put this on Steam.
Hope you think about it!