Your sprites are nicely drawn.
The movement works good.
The theme fits because the helpers drag the boss to the right and make it easy.
The orbs are like a wall when you touch them. You could set the collision on triggerd so you won't collide with it and just collect it.
I didn't understand how to defeat the boss. I spawned all the helpers with Q and picked up the sword and tryed to slay it by clicking with the mouse.
I saw that the sword was swinging but I don't think I have actually hurt the boss.
It would be cool if you would have added some sounds and music to your game.
For some sounds you could use SFXR. It's a free software for short sounds like jump, shoot, explosion, damaged etc...
For the music you could use a free software called Bosca Ceoil. Brackeys has made a tutorial on it.
I hope my little comment is usefull and I hope you'll have a lot of fun creating games in the future.
edit: sry that my comment was posted multiple times at first. It kinda bugged around when I pressed on "post comment" and then I thought it wouldn't have been posted so I pressed it again and so it kinda posted it multiple times :c. (I deleted the other comments again so there should now be just this one.