Moving obstacle is a unique addition to classic snake executed well with good art and nice music. However I would recommend a couple improvements:
- Tweaking the code so that the watermelons can't spawn on the right side as it's too dangerous to pick them up there.
- Acceleration making your snake smaller (which is inspired by Slither.io i guess) doesn't make sense as not only the game becomes much easier because of the speed you gain, it also becomes easier because of how smaller you become. This could however be easily fixed by tying up the score directly to the snake's size so the acceleration would be paid with score.