Red star rings are the game's premium currency. They can be earned during a run or boss fight, as well as from the daily bonuses and completing episodes. Red star rings can be spent to spin the companion roulette wheel, to buy normal gold rings, or to continue a run once after dying. They are best spent for gold rings. You will eventually earn eggs that will let you spin the better version of the companion wheel. You should only continue after death if you are close to a new high score. This will cost 5 red star rings and only can be done once per run. Additionally, you will lose any power-ups that were equipped prior to dying. Also, you will come back as the yellow drill for a brief period of time. If you purchase a continue during a Boss battle, you will receive a shield instead of coming back as the yellow drill. If you win, it will still be considered "flawless".