There are around 170 Black and Red cards, include split, hybrid, aftermath, and gold cards, but not cards with a Black and Red color identity, such as Soul Burn
Big box retailers like Amazon and Target are doing it too
Creatures (16) Lands (17) 17 Plains Spells (27) Originally I had Snow-Covered Plains and a couple of Faceless Havens, but the colorless source was actually a big liability in enough games that I just cut it for now (I frequently wanted to cast two or three cards in the same turn and couldnt because I had a Faceless Haven or two on the battlefield)
That being said, Commanders Sphere is also from Saturday Morning D&D
I think a deck that combines a few of these approaches and maybe throws in a couple of good* planeswalkers like Calix, Destiny's Hand, Estrid the Masked and Kaya, Intangible Slayer can be a ton of fun