Davinci Diamonds is the original Tumbling Reels slot from IGT that has since been followed up by Davinci Diamonds Dual Play,
a rather mundane take on the original in my opinion.
I've never really been a fan of Tumbling Reels slots but this is the GrandDaddy of them all if they are your thing. It has a free spin feature as demonstrated in the video at the top of this page but you need the Bonus symbols that trigger it to appear on the first 3 reels. retriggers are infrequent and you only get 6 free spins, albeit with an increasing multiplier after each winning spin.
Davinci Diamonds has been cloned due to it's long-lasting popularity anyway and games like Pixies Of The Forest and Dungeons And Dragons Treasures Of Icewind Dale will appeal to Davinci fans also.