As gamers progress, they can purchase new weapons with cash or Gold, the game's premium currency. (adweek.com)
These are then redeemed towards purchasing new weapons and power - ups or upgrading existing ones. (tech-gaming.com)
You can use it to purchase new weapons at shops (which is the smartest thing to buy), more lives if you need them, and upgrades that enhance aspects like your shields. (videochums.com)