A smol update

V1.0.1: 

-Now you can see a "Threat Level": what is equal to the difficulty of the game

-New Boss added: A very big meteor will appear if you manage to get the Threat Level to 7

-Sound volume balanced

-Price fix in shop: now some upgrades are cheaper than others

-Meteor health bug fixed: the bug where the meteors had 0.00 health is now fixed