Variant ideas.

There's a Variants World submission called "Mini Match" that features a 5x5. It was declined for lack of variety.

Ok, fair enough. But how about a really long chess board, like a 20 x 1 or 20 x 2 chess board?

Sideways War was a somethingx1 and declined for lack of variety. Rowchess is 2xsomething, and got accepted, so doing that might result in decline by lack of originality.