It’s not quite “new.”
Jayzonely (former member) came up with 4 player chess and 3 player chess variants in the 1970s and he and I (with others) spent some time figuring out rules.
The 4 player game was workable. We used a variant with this same board and another variant with the side aprons being only 2 ranks deep instead of 3 ranks as in this version. We experimented with what happens when you capture an enemy king, and mostly we settled on this rule: You get to put a cap (of your color) on that king and his pieces are still in play, moving in normal turn, but YOU are moving them or directing him how to move. So you can have an allied army that can help you gang up on another player.
That was too early in time for computers so the game was played with real pieces (4 colors) on a real board made from 2 or 3 boards cut and pasted.
With 3 player chess though, the central part of the board was always gonna have to be a triangle filled with squares…so no matter how much ganja you smoked trying to arrange THAT mess there was never a workable design. We tried several but never got one that worked well.
ETA…Imma call him later and see what he can remember about the 3 player game.
Tell him hi from us.
^^Yeah, what wabbit sed.
Jayz sez hi to all.
He also tried to splain the three person board over the phone but also confessed that it had a lotta drawbacks.