Didn't we establish that Victoire is the nasty sort of toad where she's like "it's not enough that I win! Others must lose!" Like, get a f***ing life. Jesus.

En passant!

I like Anne more so at least she got that going for her.

They are playing 5d chess and the kings are on another dimension.

Maybe it's /tg/ chess?
"Pawn to D4." "Knight to E6." "I play an Island then Cloud Sprite. Pass." "I cast Fireball for 5D6 damage." "I discard two, then draw. Three of a kind." (And yeah, /tg/ playing ANYTHING never makes it past the fourth move without devolving into Calvinball.)

Anne : "My sister's king is gone, so I won !"

Victoire : "Wait, what happened to both our kings ?"

Maybe they played the game "Tempête sur échiquier" (Knightmare Chess) where some cards can transform a piece into King.