2 Player Settlers of Catan
The variant involves using a neutral player (white pieces). The neutral player starts with 2 settlements and 2 roads. The neutral player can only build roads through the coarse of the game. The neutral player cannot build on ports or buy cards. All they can do is build roads and act as a trader of resources. In order to play this 2 player variant, you need the base game and a special trading chart. Use the standard Settlers set up and rules for the most part. Seems to work well with the Cities and Knights expansion, as well.
Idea/purpose behind the neutral player
Make Settler basic game playable and interesting with only 2 players. I was satisfied with the results. The neutral player, due to his road building abilities, made the board seem smaller. Also, the neutral player could produce resources that were initially difficult for you to produce and (hopefully trade them away to you cheaply).
Placement order at the start of the game
Let's say Red goes first
and places a road and settlement. Then Blue places a road and a
settlement. Blue then goes again. Then Red places it's second road
Players, after rolling production and before passing, can declare that they would like to trade with the neutral player. The player in question declares that they want to trade and 2 dice are rolled (standard d-6 dice). The player then consults the special trading chart in order to see what the results are. The results are a proposed trade which the player who rolled the dice may accept or decline. If a 7 is rolled then no deal is declared and the players turn is automatically over!
Road Building and Resource cards involving the neutral player
The neutral player tries to build as many roads as it can through out the game. Besides trading resources, that's all it does. The neutral player cannot own a port and thus all bank trades are 4:1 ratio. If a neutral player gets 4 resources of one type that are NOT brick or lumber, then it must trade those 4 resources to the bank for either brick or lumber. This is forced and is done immediately! Examples: neutral player has 4 sheep and trades them to the Bank for 1 brick. Brick or lumber? The neutral player must try to balance his Brick and lumber resources as equally as possible. This rule influences bank trades naturally.
When the neutral player has the resources to build a road who places it? A roll off occurs between the two players. High roll places it on the board using standard Settlers rules. If a tie, re-roll.
Initial placement of neutral settlements and roads
As stated before, the neutral player starts with 2 roads and two settlements. How are they placed? Each player, say Red and Blue, at the start of the game receive one white settlement and road each for placement. These are place after their own settlements and roads have been placed (following the turn order already established).
If the neutral player starts with brick and lumber resource cards from its beginning allotment, it builds the road immediately.
If a 7 is rolled during the game, the neutral player can lose cards if it has more than a total of seven cards. (If a 7 is rolled during trading with the neutral player the player's turn ends immediately. No cards are lost to the robber and no other effect occurs).
You can only propose a trade with the neutral player once per turn. Of course, it's possible that the neutral player doesn't always have the resources proposed. You're out of luck when that occurs, but your turn doesn't end.
Optional Rule: Red player cannot trade with the Blue player at all during the game. All trades are port deals, bank trades and neutral trades.
These rules were created by db3000 over at boardgamegeek.com (unfortunately he doesn't leave any contact info...).