4pc is moving to variants soon, and we have atomic.
I added 'Double Decker' as a starting position
https://www.chess.com/variants/custom
So we can try this already right now 
Add atomic and try to get a game going ..
Atomic Four Player Chess
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Mar 12, 2021
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#2
New variant for 4 player chess (should be workable in all modes (solo/ffa/teams)). In a regular board position for teams there is a forced mate on 1.75 (all get 2 moves except green (who is king captured)). So to resolve this add some frontal pawns to the board and you have a successful atomic chess game. Board would look like this, rule variants EnPassant, and Atomic.
FEN 4:
R-0,0,0,0-1,1,1,1-1,1,1,1-0,0,0,0-0-
3,yR,yN,yB,yK,yQ,yB,yN,yR,3/
3,yP,yP,yP,yP,yP,yP,yP,yP,3/
4,yP,yP,yP,yP,yP,yP,4/
bR,bP,10,gP,gR/
bN,bP,bP,8,gP,gP,gN/
bB,bP,bP,8,gP,gP,gB/
bK,bP,bP,8,gP,gP,gQ/
bQ,bP,bP,8,gP,gP,gK/
bB,bP,bP,8,gP,gP,gB/
bN,bP,bP,8,gP,gP,gN/
bR,bP,10,gP,gR/
4,rP,rP,rP,rP,rP,rP,4/
3,rP,rP,rP,rP,rP,rP,rP,rP,3/
3,rR,rN,rB,rQ,rK,rB,rN,rR,3
If this could be added, it would be a cool way to introduce/incorporate atomic chess into 4 player chess.
*Another possibility (will check this to make sure it is not a forced win), is to use the "Omatamix Setup" to play atomic (will update this post when I have checked for forced win).
*Note I already have atomic 4 player chess logic, and wouldn't mind contributing to making this a reality.