Vamprotector Hidden Stage

Doing a little work on my fan-game this weekend.

Always been a fan of pinball machines and pinball video games (Like Alien's/Devil's Crush). Thought it would make for a great hidden stage.

Would love some feedback. I want to add hidden gameplay types within the stage. (Like Multi-Ball or maybe a flame ball) Right now, if the player get's a high enough score (without losing all their lives) a mini boss will appear to be destroyed. If the player is able to defeat the mini-boss without fail then the player will be awarded with some extra lives for the main game.
https://youtu.be/_uNwNyqu-ic