From Exodus3000 Wiki

Abandoned Homesteads are homesteads that were left inhabited by inactive players. Abandoned Homesteads have an explore option which allows a player to find bonuses such as Mars Dollars and cards (with exception of Exploration Cards), although they sometimes have already been picked clean, by other players.

Currently, when a new player signs up, they replace an Abandoned Homestead, so these will become rarer as time goes on.

Note: A homestead will become Abandoned after a player is inactive for a 3 month period.

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