> allowing all players to bid on every single unowned property that a player lands on
This seems to have been the rule from Magie's 1923 patent.
"1. Land in Use - A player stopping on this space is supposed to be occupying and using the land, and pays to the owner thereof the amount of land rent indicated. If there is an Improvement on the land, he pays $100 in addition to the land rent. If a player is himself the owner of the space, he takes from the board the amount of rent indicated. If the space is for sale, that is, if the corresponding card is still on the board, all the players bid for it, the highest bidder paying to the board the amount of his bid and taking the card into his hand.[...]"
https://www.google.com/patents/US1509312
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edit: and the 1906 rule, except that the landing player just has to meet the highest bid, not beat it.
"RULE 7. Land Rent. --- When a player stops upon a lot owned by another player, he must pay the land rent to the owner. If he stops upon one of his own lots he pays nothing. If the lot is not yet owned by any of the players, it is "For Sale" and the player stopping upon it may purchase it at the original sale price, provided no other player bids more for it. If the player who has stopped upon it is willing to pay the highest price bid, he has the first option. If he cannot or does not want to pay the highest price bid, then the player bidding the highest price must take the lot at the price he has bid for it. If the first player does not by a lot and some other player does, the first player pays the land rent to the purchaser. If no player buys it the land rent is paid into the PUBLIC TREASURY. If the lot is thought the purchaser or takes the corresponding Title Deed card from the pack."
http://landlordsgame.info/games/lg-1906/lg-1906_egc-rules.ht...