Check out the special «Daily Tankoins Pass» offer. After you purchase this offer, you instantly get 500 tankoins and will unlock completed daily special missions for the next 30 days. Every day, you will get one of these missions – simply enter the game and claim your 150 tankoins. From these special missions, you can obtain up to a total of 5000 tankoins at the end!
Each mission is available for 1 day only, so it means that you need to claim your reward every day or you will miss your 150 tankoins for that day. You do not need to play or do anything else – just claim the rewards.