Why do bullets hit each other?

Because it adds a lot of depth to the game :)

In Blaston all bullets have Health Points (HP). They also have Collision. Collision is our word for ‘Damage to bullets’.

So if a bullet A with HP 10 and Collision 20 hits bullet B with HP 15 and Collision 5, A will go on its trajectory with HP 5 remaining and B is destroyed.