My family's board game of choice is Catan. We've probably played close to 50 games of it in my lifetime. Many years ago we started experimenting with some very small homebrew rules, and more recently I saw real-time Catan, which we played two games of. Even after two games it was clear to us that real-time Catan is an enormous improvement, and I doubt we'll ever go back to regular Catan again.
That said, we did find we needed to tweak the rules. Here's our full homebrew ruleset, building off cities and knights + seafarers:
- Turns have a set time limit. We generally start with 45 seconds a turn, and increase to 60 seconds later in the game if it's clear people need more time for more complex turns.
- You may take any action on anybody's turn, including trading with anyone else.
- The only exception to this is progress cards, which must be played on your turn.
- When a player takes an action that requires a response from another player (e.g. master merchant), pause the timer for all players.
- When a player reaches 13 victory points, the game does not end immediately. Instead there is an (indefinite, but reasonable) rebuttal period for the remainder of the turn where players continue to play.
- If a player still has 13 VPs at the end of the turn, they win.
- If two players are tied for VPs at the end of the turn, play continues until one player is ahead at the end of a turn.
- If any actions conflict, ties are broken by turn order, with the person who's turn it is having priority, and so on continuing clockwise.
- You may declare any progress card you own as tradeable by placing it face up in front of you.
- You can barter with other players using tradeable progress cards as you would any other resource.
- They are still progress cards in every respect. They count toward your progress card limit, they can be stolen by the spy, and you can still play them.
All other rules that interact with turns are still in play: you cannot play a progress card on the same turn you recieve it, the player who rolls a 7 moves the robber, etc. The purpose of the rebuttal period is to deter players from waiting until the last second to reach 13 victory points. And the purpose of not immediately ending the game when a player "wins" is to avoid a mad rush to reach 13 victory points before anyone else on a turn! Requiring progress cards to be played on your turn is both to nerf them, as we found they were otherwise too powerful, and to reduce the potential for conflicting actions.
In my opinion, breaking ties by turn order is more elegant than casually deciding each case at the table, as the original post described. We found conflicting actions to be a large problem – they only happened ~once a game, but could turn the course of the game (such as a wedding played right as someone builds a settlement).
While we're on the topic of homebrews, we've long been searching for a way to make the green commodity's ability in cities and knights less powerful, but haven't found anything thematically satisfying while not nerfing it into the ground.
Thanks to Robert O'Callahan for describing the original idea!