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Some questions about this variant:
1. If you can make this switch in check, then I would think it could be used to escape checkmate as well, thus changing the definition of checkmate.
2. If the king is on the second rank can he move 2 squares forward if an enemy pawn has been captured?
3. If the kings are a knights move away from each other and both players have lost a knoght, does that mean that check is impossible, since the checked king could move like a knight and capture the enemy king?