Weapons are not purchased permanently. Instead, they will only last for two hours. Only spend your coins on the best weapons. Consider using the Quad Guns if possible. Choose a gun that suits your play style and repeatedly purchase it to use it skillfully. You do not have to purchase all the previous weapons to unlock a new one. Weapon upgrades and power-ups that are collected may change your current weapon. However, collecting power-ups is useful because they increase the chance of getting a sidekick.