Sure. So basically we took the non-creature cards in MTG and adapted them to chess. Instead of two decks, it was a communal deck, and you could forgo a turn to draw another card. Then we just adapted Enchantments/Sorceries/Instants to be more "chess-flavored".

One of the tricky parts we discovered in playtesting was that you can’t let a card’s effect trigger immediately. Instead, when a player plays a card, it goes into a sort of “escrow” state. They declare the card, everyone knows it’s coming, but it doesn’t take effect until the next round.

So the flow is: a player commits to playing a card this turn, and then on their next turn that card’s effect resolves.

Without this delay, instant effects made it too easy to pull off cheap wins for example, using a teleportation or transposition card to immediately force a checkmate with no chance for the opponent to react.