Before using The River and/or The River II you may want to avoid arguments by agreeing the following points:
The complications regarding "U" turns are fully explained in the section below, together with an optional rule you can use if you want to ensure a tidy, complete river (the official rules do not require the river to be completed).
The other two points are simpler. The statement from Hans im Glück is "Officially, the farm goes around the spring. So it is a connected farm. I personally prefer to use it as a division, since otherwise, despite the river, there is still only one large farm." So you just need to make a decision as you start the game as to whether there is one farm on that tile or two.
Which tiles should you use if you want to combine both sets of river tiles? You now have too many springs and lakes. The official ruling is very simple – just discard one spring and one lake, so that you make one complete river with two branches.
I would recommend discarding the volcano/lake if you are not using The Princess & The Dragon, and keeping it in if you are.
Personally I find 22 tiles is too long a river, so sometimes we just use a selection of interesting tiles to make a river-length of our own choosing, making sure that the number of river-end-tiles is the same as the number of branches.
What is a "U" turn?
The original rules state "a river tile may not be placed so that the river makes a "U" turn". This has generated many queries. The official response from Hans im Glück is that only immediate "U" turns are prohibited.
This can still lead to some confusion, especially when you add the branch from "The River II".
Some other basic principles to be remembered are:
Applying the same logic to rivers it follows that:
<![if !vml]><![endif]>Being specific on what you can and can't play, this is the basic prohibition – two adjacent curves, placed to curve in the same direction:
On the other hand, this is a permitted "U" turn since it is not "immediate":
If you are using the river branch from River II then these plays are all technically illegal, though of course the curved river tile can still legally be played, just in a different orientation or in a different place:
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<![if !vml]><![endif]>The complications start to arise when multiple wide "U" turns are used as in this example. Although the last tile placed was a legal play, it has left the river unfinishable. Following the basic principles stated above, this is not a problem. The next player just picks up each of the remaining river tiles and the lake and discards them, then continues with the normal tiles. The river remains unfinished.
The official ruling from Hans im Glück is "Try to think while playing. Players may have an unfinished River...but it‘s their own fault."
Note that it is illegal to join the two branches to form a circular river:
Of course, if the tiles are played to this position, the river is again, unfinishable.
If you decide that you want to avoid the possibility of an unfinished river, as in these last two situation and make sure that you always have a complete river, ending in a lake (especially if you are using "The River II" and want to play the lake/volcano tile in order to get the Dragon into play early), then you need an extra rule. The simplest one I have been able to state is:
Optional Rule: "Each river tile must be placed so that it would still be possible to play whichever river-ends are in play if they were the next tiles to be played." (You may have to discard a few tiles, but at least this keeps things simple and consistent and you can finish the river.)
<![if !vml]><![endif]>Invoking the optional rule: Completing the circular river above is illegal, but with this optional rule, the one before it is also illegal, since it prevents the river ends being played:
<![if !vml]><![endif]>Invoking the optional rule: And in the other example above, this would also now be an illegal play:
<![if !vml]><![endif]>Invoking the optional rule: Even if the loop is bigger, playing a tile like this would be illegal:
If you were using "The River" and "The River II" combined, then yes, the next two tiles might be curves which could be played legally to allow the river to be finished, but that would require someone to look at the next two tiles to make sure that it would work. It is much simpler just to make such plays illegal, then you know that you can finish the river without worrying about what is left in the pile.
This document was produced by John Sweeney. Please send any comments to firstname.lastname@example.org