Honestly, what you've got so far is pretty fun! :)
No critical issues found by me atleast, will say the worm really like to get out of hand :') I spent like a whole 3 minutes on one of the waves dealing with an ever-replicating worm o-o.
A few possible things to thing about, might wanna reduce the amount of text on the tutorial, the slingshot mechanic is neat and I wonder if it would be more fun if you let the player click and drag from anywhere on the screen rather than having to click on the player*
I lost a run to clicking outside the box onto a link while slingshotting...so I'm a bit sad there too :'] ....
Overall though, great job on getting this finished! It was fun! x]