Thank you for playing!
For the aiming mechanic:
- click and hold somewhere in the screen and drag it to aim (you have to drag it far enough until you see an arrow icon near the slingshot). In this state, you can change the aiming direction based on the direction of your current mouse position to the point that you firstly clicked on.
- release the click to shot.
I know it's a bit confusing to read, but if you try it yourself, it won't be that hard to understand hopefully :)