Hi, there,
I like the concept of protecting your gold and the dragon design is very nice.
Small point of improvement:
Moving the dragon is a little too slippery. The deceleration value could be a bit higher to make it stop faster.
It's important to provide feedback when you hit an enemy to realize the impact you're having (flashing, particle effect).
The hitbox for collecting coins is a bit small, and only at the dragon's paw level. It could be more generous.
I hope you find this feedback useful.