I love Marco Polo.
Thanks for implementing, but something appears to be strange.
it happens with the personnage 'Mateo Polo'
When getting a new contract at the beginning if the round and already own 2 in the contract box of the player board, I expected to select those I want to keep but the game discarded the contract I selected without being able to move back.
As it is for contract we fulfill, it seems more natural to select the contracts we want to keep than the one we wish to discard, especially if not being able to undo.