I've used Google Ads in the past but they didn't have any Ad Rewards... then I transitioned to using AdinPlay (https://adinplay.com) which does support mobile and Ad Rewards.
Ahh I forgot to mention last time I worked with Google Ads was 2012 lol!! I'm pretty sure that didn't exist then... I never saw a Flash game with ad rewards at that time and never heard of it myself then.
https://admob.google.com/home/resources/rewarded-ads-win-for...
Disclosure: I work at Google, but not in ads, and know very little about ads.