Interesting idea. They should play around with this as a variant.
"u can not play u r partner already played pieces
example :-if its red player he move king then in yellow turn he can not move same king the red already played!"
What if you have to (to move out of check, or save a piece or mate or something like that)?
TEAM MODE
these is like going backward make normal chess on 4 player broad with 4 players these is fully supportive teaming no restriction there no (me or yours) its white team vs black team!
rules required
1.u can play u r any team pieces( u r partner side or u r side! )
2.u can not play u r partner already played pieces
example :-if its red player he move king then in yellow turn he can not move same king the red already played!
3.cap the king !
add cross turning to it make it more close to normal more interesting i see is normal turning