I am an active player on four player team chess on chess.com (my Elo is currently 2095). I am planning to write something about theory of opening of this chess variant. Question is, do you know if something like this already exists ? I find nothing on the internet. Moreover, I am also a programmer and I have this project to code a CPU for this kind of chess, do you know if somebody has already coded one ? I think it will be very difficult to write one (essentially for the CPU to evaluate the position) so that's why I am looking for pre-existing code.
I doubt there is any existing theory for four player chess, because it is not widely played or analyzed. I'm not sure if there even exists any serious investigation of the overall strategy or tactics of this variant, as it is mostly a novelty game played casually. It's pointless to analyze openings when even the basic strategies of a game are largely unknown.
I also suspect that the game itself is not really well suited to opening analysis in general, due to the increased size of the board and number of pieces. This also makes writing an engine significantly more difficult.