Nos

Introduction

This is a Dutch domino game for 3 to 5 players in which the loser of each hand chooses the rules for the next hand on the basis of the dominoes he or she is dealt. There are options to play with touching ends matching (normal dominoes) or with touching ends adding up to 7 (as in Matador or Russian dominoes), with tiles played either in a single line (two ends) or a cross (four ends) or in special cases a triangle (three ends). The game has a good balance of luck and skill. Part of the fun is choosing rules that will give you the best chance to play all your tiles. There are also opportunities to win extra chips by timely play of doubles or by creating a blocked position.

This description is based mainly on the book Domineren en Nossen by Ir. D.H.G Brethouwer (Van Goor Zonen Gravenhage, 1967) and describes the version played at the Nos-club 'de Haaien' in the Witte Societeit, The Hague. The society still exists, but no longer includes a domino club so far as I can tell from its website. We would be very interested to know whether this game is still played in the Netherlands or elsewhere. We would like to hear from any players, especially if they can help us to resolve the doubtful points in the rules.

This page was originally drafted by Günther Senst, and was edited by John McLeod in October 1996 and 2015. There are a few places where the book rules are not completely clear. We have interpreted them as well as we can and listed the uncertainties in the notes at the end of this page.

Preparation

Three, four or five people can play. A double-six set of 28 dominoes is used. It is traditional to use chips for scoring; before the start of the game, each player receives 500 units - 4 hundreds, 4 twenties, 4 fours and 4 ones. When playing for money, players agree the value of a 20-point chip and the final settlement is made in multiples of 20 points only.

The first play of each hand is called the set, and the player who begins is said to be on set. In the first hand this is the player who holds the highest double. In subsequent hands the player on set is the loser of the previous hand - i.e. the player who held the greatest pip value of tiles at the end of the play.

The Deal

The 28 tiles are shuffled face down on the table - for the first hand anyone may shuffle; in subsequent hands the tiles are shuffled by the player to the right of the player on set. Then each player in turn, starting with the player on set and continuing clockwise takes the proper number of tiles, which is 8 minus the number of players - i.e. 5 tiles if there are 3 players, 4 if there are 4 and 3 if there are 5 players. Each player places his tiles on edge so that they are visible to himself but not the other players.

A stock of 12 or 13 tiles will remain face down on the table. This is called the boneyard.

The Set

For the first hand the player on set is the player with the highest double, and he has to play this double, double blank counting low. If no player has a double (theoretically this can happen once in 700 games) the tiles are put back and there is a new shuffle.

For hands other than the first, the loser of the previous hand is on set. He must play a double: having more than one double he has a free choice of which to play. If he has no double, he must draw a tile and play that tile, whether it is a double or not. The "loser" who starts the next hand is the player who had the largest spot value of dominoes remaining in hand at the end of the play (0-0 counting as 14). If two or more players ended with an equal spot total, they each draw a tile from the shuffled deck and the player who drew the tile with the higher spot value starts the next hand. [1] Note that the "loser" might not be the player who lost most in chips in the previous hand.

When the player on set begins with a double from his original hand, he is paid the point value of one end by each opponent, for example 4 points each for the [4-4]. If it is the double blank he receives 7 points from each. If he had to draw a tile and it is a double, he gets double the amount of points from each player (for example 8 instead of 4 for the double four). If the drawn tile is not a double, instead of receiving points he has to pay to each opponent the total spot value of the domino (e.g. 9 points each for the 5-4, 2 each for the 2-0).

Immediately after playing the first tile, the player on set announces which type of game will be played. There is a choice of ordinary or matador-style matching, the layout can have two, three or four ends, and there are further options. These are all explained below. Whatever rules are chosen, the object is to play all your dominoes to the layout before the other players. The first player to run out of dominoes declares 'nos' and wins 5 points from each opponent.

Immediately after the player on set has announced the kind of game to be played, players with more than a certain number of doubles can declare them if they wish to, and receive payment from each of the other players. The doubles are placed face up on the table in front of the owner and they remain there until played to the layout. The number of doubles which can be declared and the payment for them depends on the number of players as follows:

Payment for: 3 players
(5 tiles each)
4 players
(4 tiles each)
5 players
(3 tiles each)
3 doubles --- 25 50
4 doubles 200 250 ---
5 doubles 500 --- ---

The Play

After the first domino has been set and the game announced, the play continues in clockwise rotation beginning with the player to the left of the player on set.

Each player must if possible play one tile when it is his turn. Before playing a tile, the player is allowed to draw as many tiles as he wishes, one at a time, from the boneyard, provided that at least two tiles remain in the boneyard.

If a player has no tile that can legally played, he must draw tiles from the boneyard until he is able to play, or until only two tiles remain. If a player has no legal play and there are only two tiles left in the boneyard, that player must pass and the turn passes to the next player in rotation.

Payment for doubles

A player who plays a double next to the tile just played by his immediate predecessor receives from his predecessor a number of points equal to the number of spots on one end of his double (7 points for the double blank). The player has to ask for these points in order to receive them.

Please note that (as explained further in note [2]):

  1. There is also no payment for playing a double if the predecessor has just played his last tile.
  2. The player of a double does not receive payment if one or more players have had turns between the play of adjacent tile and the play of the double, even if the intermediate players passed without playing a tile.

Immediately after the player on set announces the game to be played, any player who has a double that fits on the first tile can play it at once, without waiting for his turn, and receive payment as above from the player on set. Later, when the player's normal turn comes, instead of playing he must miss this turn saying 'I wait', and the turn skips to the following player. Example: player A is on set without a double, draws the [3-2], pays 5 points to each opponent and announces 'ordinary dominoes'. Player C, holding the [3-3] immediately plays it and claims another 3 points from A. Now B plays the [2-6], C must say 'I wait', and it is D's turn to play on the 6 or the 3.

When the starting tile is not a double, it may sometimes happen that more than one player has a double that fits on the first tile. In this case all such doubles can be played immediately and all are paid for. [3] It is also possible that one player may have two doubles that fit the two ends of the first tile. In this case the player can immediately play and be paid for both of them, and must then miss two turns, saying 'I wait', before playing again.

The Possible Games

The list of possible games may seem long and confusing at first sight, but really it represents different combinations of just three choices.

  1. Geometry. The layout can be a single line, in which dominoes can be added to either of the two ends. Alternatively, when the set tile is a double, the layout can be a cross. In this case the next four tiles must be adjacent to the set, starting the four arms of the cross. Only when these four tiles can be played can the cross be continued. There is also the option to require the second tile on each arm of the cross to be another double. This arrangement is called a double cross. A third option, which is possible only when the set tile is the double blank, is a triangle. The next three tiles played must be the other three matadors [6-1], [5-2] and [4-3] on three of its sides to begin the three arms.
  2. Matching rule. The two basic possibilities are ordinary, in which each new tile must be placed with one of its ends against an open end of the layout with an equal number of spots, or matador, in which the spots on touching ends of adjacent tiles must add up to 7. When matador matching is used, the [0-0], [6-1], [5-2] and [4-3] are wild 'matador' tiles that can be played on any open end, but the next tile played on a matador must obey the matching rule in force. With the cross formations it is possible to specify that the matching rule changes from ordinary to matador or vice versa when the initial cross is complete. It is also possible to specify ordinary matching on one end of a single line or two arms of a cross and matador matching on the other end(s).
  3. Conditions. When choosing a single line it is possible to impose various conditions on which side must be played first, and also to change to the opposite matching rule after the condition is fulfilled.

Here is a complete list of the types of game which can be chosen by the player on set. [4]

1. Ordinary dominoes.
The layout extends in two directions from the first tile. Each domino played must have an end which matches (has the same number of spots as) the free end of a domino at one end of the layout. The domino is played with its matching end next to the domino it matches, and the other end free to be matched by a future play. Doubles are traditionally placed crosswise, but this has no special significance for the game - for matching purposes a double counts as the number of spots on one end.

Example:
ordinary dominoes

2. Ordinary cross dominoes.
The first tile must be a double. The next four tiles played must have one end matching the number of the double; they are played with the matching end inward, so that a cross is built. Only when the cross is full can further tiles be played, extending any of the four arms of the cross, according to the rules of ordinary dominoes.

Example:
ordinary cross dominoes

3. Ordinary double cross dominoes.
The beginning is the same as in ordinary cross. After the cross has been built, the next tile played to each arm must be a double matching the free end of that arm of the cross. Once a double has been played to an arm, it can be extended by playing further dominoes according to the rules of ordinary dominoes. An arm can be extended as soon as its double has been played - it is not necessary to wait for the other doubles.

In the following example the top arm requires the 6-6 next and the left arm requires the 4-4:
ordinary double cross dominoes

4. Matador (also known as Russian dominoes).
The procedure is similar to ordinary dominoes, but with a different matching rule. The ends placed together, rather than being equal, must have a total of seven spots (so a 1 matches a 6, a 2 matches a 5, and a 3 matches a 4). There are four special tiles, called Matadors. These are the tiles which have a total of zero or seven spots: the 6-1, the 5-2, the 4-3 and the 0-0. A matador may be played against any tile. When playing next to a matador, the free end must be matched in the normal matador way - that is making a total of 7 spots. Therefore a player playing a matador should choose carefully which of the two ends should be an open end. Doubles as well as matadors are arranged in a straight line. Notice that the only tiles that can be played on a blank are the matadors. On the other hand you are not allowed to match a blank end to a matador on the layout - thus tiles containing a blank can only be played with their blank ends facing outward.

The following example was started from the 6-6:
matador (russian) dominoes

5. Matador cross.
The first tile must be a double, but not the double blank. A cross is then built, as in type 2 (ordinary cross), but following matador rules (the inner ends of the dominoes must total 7 with the number of the double - or matadors can be played). When the cross is complete, the four arms are extended according to matador rules.

Example:
matador cross dominoes

6. Matador double cross.
This begins like matador cross. When the cross is complete, the next tile on each arm must be either the appropriate double (using matador matching rules) or a matador. These doubles or matadors are not placed crosswise. The four arms are further extended following matador matching rules - you can add further tiles to an arm as soon as its compulsory double or matador has been played, without waiting for the other arms.

In the example, the top arm can only be extended if the 4-4 or a matador is added to it:
nos6.gif - 2.41 K

7. Ordinary cross, then matador.
The first five tiles are played as in ordinary cross; then the arms are extended using matador matching rules.
8. Ordinary cross, then matador double cross.
The first five tiles are played as in ordinary cross. The next tile on each arm must be a double, matching according to the matador rules, or a matador. Then the arms are extended using matador matching rules.
9. Matador cross, then ordinary dominoes.
The first five tiles are played as in matador cross; then the arms are extended using ordinary matching rules.
10. Matador cross and then ordinary double cross dominoes.
The first five tiles are played as in matador cross. The next tile on each arm must be a double, equal in number to the free end of the arm it is played on. Then the arms are extended using ordinary matching rules. Notice that in this case if one of the arms of the cross is begun with a double, it cannot be extended further. For example if the set tile is the [4-4] and one arm of the initial cross is the [3-3], the next tile on that arm would have to be a double matching the [3-3], which is impossible.
11. Ordinary or matador dominoes with conditions.
These extra conditions can be specified by the player on first set when naming a single line game. The possible conditions are:
  1. 'First here and then there', which means that the player first on set specifies that the second tile must be played on a particular side of the first tile, and third tile must be placed on the opposite side. For example the player on set has no double, draws the [5-3] (paying 8 to each opponent) and chooses ordinary dominoes first here (pointing to the 5) then there (pointing to the 3).
  2. As an alternative to (a), the player on set can specify that a particular number of tiles (up to four) must be played on a particular side of the first tile before any tiles can be played on the other side. Normally one would specify 2 tiles if there are 3 players, 3 tiles with 4 players and 4 tiles with 5 players, so that the other players are forced to play on the specified side and the player on set can play on the other side at his next turn.
  3. As an additional condition, the player on set may specify that after the tiles demanded in condition (a) or (b) have been played, the matching rule changes from ordinary or matador or vice versa. For example the player on set draws the [5-3], pays 8 each and says 'ordinary dominoes first here' (pointing to the five) 'and then there' (pointing to the three), 'and after that matador'. In that case the first tiles played against the [5-3] must follow ordinary matching rules, but after those tiles have been played the rule changes to matador.
A condition of type (b) does not prevent a player who has a double that fits on the 'wrong' side of the set tile from playing it immediately and receiving payment from the player on set. In this case the player of the double must 'wait' instead of playing on the first turn when it would have been possible to play in the position where the double was placed. Example. In a 4-player game, player A is on set, draws the [4-2] (paying the opponents 6 each) and announces 'ordinary dominoes with the first three plays on the 2-side'. Player C holds the double four and plays it immediately, claiming 4 points from the player on set. Now player B plays the [2-6] on the 2 and player C must play on the 6 because there are not yet three tiles on that side. Suppose C plays the [6-3] and D plays the [3-0]. Now that the required three tiles have been played on the 2-side, A can play the [4-6] on the 4-side as planned, B plays (say) the [0-0] on the other side. It is now that player C has to say 'I wait', and it is player D's turn next.
12. Volapük, volapük cross or volapük double cross.
In volapük, ordinary dominoes are played on one side of the first tile and matador on the other side. In volapük cross or double cross, ordinary dominoes are played on two opposite arms of the cross, and matador on the other two. As usual the cross must be completed before any arm can be extended first. In the double cross version the next tile must be a double on the ordinary arms and a double or matador on the matador arms. In a single line volapük game, the player on set must specify which side will be ordinary and which matador. The player on set may also impose a condition similar to 11b above that one side must be played on up to four times before the other side may be played. Example. In a 4-player game the player on set has no double, draws the [6-1], pays 7 each and announces 'volapük, first three tiles ordinary on the six'.
13. Triangle, also known as colonel cross.
The first tile played must be the double blank. Next to that, the other three matadors must be placed. After these four tiles are in place, the three arms are extended according to matador rules.

Example:
triangle dominoes

14. Triangle double cross, also known as general cross.
This begins in the same way as triangle. After the four matadors have been placed the next tile added to each arm must be the appropriate double (matching according to matador rules). The three arms are then extended using matador rules. As in any double cross game, it is not necessary to wait for all three doubles to be played before further extending the arms - further dominoes can be added to any arm which contains a double. In the following example, the next domino added to the right arm can only be the [1-1]:
triangle double cross dominoes
15. Triangle, then ordinary dominoes.
This begins like triangle, but after the four matadors have been played, the arms are continued using ordinary matching rules.
16. Triangle, then ordinary cross dominoes.
This begins like triangle. After the four matadors have been played, a blank end must be played next to to the fourth side of the double blank to form a cross. Once the cross is built, the game continues as in ordinary cross dominoes.
17. Matador, first here and then there, then ordinary cross or ordinary double cross.
The first tile can be any double. The next two tiles must be played next to the double, following matador matching rules. Then the cross is completed with two further tiles played according to ordinary matching rules. The four arms are then extended using ordinary matching rules. In the case of a double cross the next tile added to each arm must be a double.

Nos and Blocking

Nos
The first player who gets rid of all his tiles declares Nos and receives 5 points from each opponent. In the course of the game other players will get rid of all their tiles as well, but there is no special reward for that. They are simply out of the game, and take no further part until the scoring at the end.
Blocking or closing:
A player who has just played a tile and is of the opinion that no further tiles can be played in this hand can announce 'I block' or 'I close'. If he is right, each player who is not yet out of the game has to pay 20 units to the player who closed. The next player in turn will then have to draw all the remaining tiles from the boneyard, except for the last two. If it turns out during this drawing of tiles that the closing was not correct, the player need not go on drawing of course. If the closing announcement is wrong, the player who closed incorrectly has to pay 40 units to each opponent, and in that case the game continues normally as though there had been no announcement.
If there are only two players still in the game and one of them closes with his last tile, then the other player need not draw tiles.

End of Game, and Scoring

A game can end in any of the following three ways:

  1. only one player has tiles - after the second to last player has played his last tile, no further tiles can be played;
  2. the game is closed;
  3. all players correctly passed in succession - there are only two bones in the boneyard and no one has a legal play.

When the game has ended, each player counts the number of spots on his remaining tiles. The double blank counts 14, but other blank ends count 0. A player who got rid of all his tiles has a count of zero. Each player then pays to every player with a lower count than himself a number of units equal to the difference between their scores.

Settlement

It is customary to play for so much per point, rounding each player's final chip total down to the next multiple of 20. At the end of the session each player keeps a multiple of 20 chips and the excess chips are placed in a pot to one side. For example a player with 476 chips will keep 460 and contribute 16 to the pot. To decide who receives the chips in the pot it is traditional to play Billitonnen, a domino game of pure luck which is a variant of Blind Hughie. The winner of this game collects all the excess chips so that everyone now has an exact multiple of 20, and each player then pays or receives according to the amount he or she has below or above 500.

A player who wants to stop playing in the middle of a session rounds his or her chips down to the nearest 20 and puts any remainder into the side pot. This player will pay or receive from the other players according to the difference of the rounded total from 500, and has no claim to the side pot.

Tactics: Choice of Game

When you are on set, the aim is to choose a game that will give you the best chance to play all your tiles without drawing, preferably while making if difficult for the other players to play. In some cases the choice is clear. For example if you have the [5-5] and some other fives, you can set the [5-5] and play ordinary cross dominoes. Hopefully at least one of the other players will be short of fives and will have to draw in order to play on the cross.

If you have more than one double, for example something like [5-5], [5-4], [4-4], [5-1] in a four-player game, you can choose ordinary double cross and set the [5-5], with the certainty that you will be able to play the [5-4] on your second turn, and later add the [4-4] to that arm since no other tile would be allowed there. Ideally, if the play goes something like [5-5], [5-0], [5-2], [5-6]; [5-4], [2-2], [2-1], [6-6] you can now play the [1-5]. Now there is one arm that can only be continued with the [0-0], one that requires the [5-3] (the only remaining five), one that needs your [4-4] and only the 6-arm is open to a variety of tiles. Hopefully at least one player will have to draw tiles before you declare nos with your [4-4].

Matador games are attractive when you hold at least one matador. With a combination of matadors and doubles there are other opportunities, for example with [2-2], [4-4], [3-2], [6-1], you can declare 'ordinary cross then matador double cross' and set the [2-2] on which you can play the [2-3] and then the [4-4], having first placed your matador on some other arm.

If you are lucky enough to hold the [0-0] when on set, then some form of triangle (games 13-16 above) will often be your best choice, since anyone without a matador will be forced to draw until they find one. If you have a second matador in your hand and there are at least four players you can guarantee that the whole boneyard will be drawn before your second turn.

The worst hands are those with no matadors and no doubles. If you hold something like [3-2], [5-3], [6-2], [3-0] in a four-player game and draw the [3-1], probably the best you can do is volapük starting with three tiles ordinary on the 3-side. Since you have several threes you can hope that the next player will have difficulty playing on the 3. Also you should be able to play your [6-2] on the matador side at your next turn, though there is a risk that this will go wrong if someone is able to play the [6-6] immediately on the 1-side.

Procedures and Penalties

The penalty for drawing too few tiles at the start of the game is to pay 40 points to each opponent and draw additional tiles until you have the correct number. This penalty can be exacted by the other players any time after the offending player has set his tiles on edge in front of him, but before the first tile is played. If the offender is on set, the penalty can be demanded any time before the second tile is played. Once a player other than the offender has played a tile, the penalty lapses, and the offender no longer has to draw tiles to make his hand up to the correct number of tiles.

There is no penalty for taking one or two tiles too many at the start of the game. The offender can return the extra tiles to the boneyard if he has not yet looked at them (otherwise he must keep them). A player who took more than two tiles too many pays a penalty of 40 points to each opponent.

If the player on set has a double, but draws from the boneyard instead of playing the double, the penalty is again 40 points.

Once a player has played a legal tile and let go of it, the play cannot be changed.

If a player who has played a double ahead of his turn in the first round forgets to say 'I wait' when his proper turn comes, but instead tries to play another tile, he has to pay 40 units to each opponent.

If a player opens the game with a double, there is no obligation for the other players to pay for the double if the first player had too many tiles at the beginning of the game. A player who wrongly asks for payment for a double has to pay 40 units to each of the other players. Similarly, there is no obligation to pay a player who declares doubles, if that player took too many tiles at the beginning of the game.

A player who tries to draw from the last two tiles in the boneyard, or who passes when there are more than two tiles in the boneyard, has to pay 40 points to each opponent. In addition, a player who passed illegally has to draw until he can play a tile or there are only two tiles left. If after his play it is discovered that he had passed while able to play a tile, the penalty is 80 points to every player.

A player who declares Nos while he has still tiles, pays a penalty of 40 points to each opponent.

Players who have no tiles left must not give advice or hints as to the play, but they are allowed to point out mistakes in play. The penalty for breaking this rule is to pay 40 points to each other player.

If the game was closed correctly, the player next in turn has to draw all tiles remaining in the boneyard except for the last two. If he does not draw and it is noticed, he has to pay 40 units to every player.

Other penalties of 40 units to every player in addition to the cases mentioned above:
a) playing a tile which does not follow the rules of the announced game,
b) playing the first tile if you are not on first set,
c) playing a tile out of turn, (except the playing of a double on the set tile in the first round),
d) playing a tile instead of saying, 'I wait' when you played a double out of turn before,
e) asking for payments which you are not entitled to,
f) if a player covers one or more tiles with his hand or otherwise so that one or more opponents cannot see this tile or these tiles,
g) displaying ones tiles face-up on the table (except when declaring doubles of when required to as a penalty)

In the cases (a) to (d) the incorrectly played tile must be taken back and lie face-up in front of the player until legally played. In case (a) the player must take back the tile and play another tile.

Summary of Nos

List of possible games

  1. Ordinary dominoes
  2. Ordinary cross dominoes
  3. Ordinary double cross dominoes
  4. Matador
  5. Matador cross
  6. Matador double cross
  7. Ordinary cross (the first five tiles) and then Matador
  8. Ordinary cross and then Matador double cross
  9. Matador cross (the first five tiles) and then ordinary dominoes
  10. Matador cross and then ordinary cross dominoes
  11. Ordinary or Matador construction with condition and then change
  12. Volapük - ordinary, cross, or double cross
  13. Triangle
  14. Triangle double cross
  15. Triangle (the first four tiles) and then ordinary dominoes
  16. Triangle and after the playing of a blank end to the double blank ordinary cross
  17. After any double, Matador "First here and then there", and then ordinary cross or ordinary double cross

Payments

  • First tile a double played from hand - receive the spot value of one end from all players (double blank is worth 7);
  • First tile a drawn double - receive the spot value of both ends from all players;
  • First tile drawn and not a double - pay total spot value of both ends to all players.
  • Double placed on the tile played by immediate predecessor, or out of turn on the first tile - receive spot value of one end from the player of the previous tile.
  • For declared doubles you receive from every player:
    • 50 points for 3 doubles out of 3 tiles,
    • 25 points for 3 doubles out of 4 tiles,
    • 250 points for 4 doubles out of 4 tiles,
    • 200 points for 4 doubles out of 5 tiles,
    • 500 points for 5 doubles out of 5 tiles.
  • Nos - the first player who gets rid of all his tiles receives 5 points from everybody.
  • Declared blocking or closing of the game - the player who closes receives 20 points from all the players who are not yet out of the game.

Notes

Here are some points on which Brethouwer's book is not completely clear. If you prefer a different interpretation, or better still if you are a Dutch Nos-player who knows that the game is played differently from our description, please feel free to get in touch.

  1. The book says that the 'big loser' (de grote verliezer) is on set for the next hand, and the term grote verliezer is defined in the chapter or ordinary dominoes as the player who ended with the highest spot value of dominoes (p14, rule 7). We assume that it has the same meaning in Nos, but this will not necessarily be the player who lost most chips. In fact it would sometimes be awkward to determine who had lost most chips in the course of a hand given the possibility of payments for doubles, penalties and so on. The chapter on ordinary dominoes also specifies that a tile is drawn to decide the winner if there is a tie for least points in a blocked game, so we assume that the big loser is determined similarly in case of a tie.
  2. The book gives the following rule about being paid for a double played on the previous player's tile: 'Waneer er één of meer beurten van andere spelers tussenliegen, geldt deze regel dus niet, en ook niet als de bedoelde voorganger de nos heeft.' (Whenever one or more other players had turns in between, this rule does not apply, and also not if the predecessor in question has 'nos'.) This leaves it slightly unclear whether you have to pay when the next player plays a double on a tile with which you went out of the game but did not make 'nos' because you were not the first to go out. Also it is not quite clear whether you have to pay when the next player passes without playing and the player after that plays a double on your tile. Fortunately both these situations can be found in the examples of play given in the book.
    1. On page 43 in a matador cross player A makes nos, then player B goes out with the 4-4 receiving nothing, and then player C goes out playing the [3-3] on the [4-4] also receiving nothing. So you don't have to pay when a double is played on the tile with which you go out of the game, even if you are not nos.
    2. At the bottom of page 54 in an ordinary cross game player A plays the [3-0], player B passes and player C plays the [0-0] receiving nothing. So you don't have to pay if the double is played after a pass.
  3. There is a theoretical possibility that in an ordinary matador game three people might want to play doubles immediately even though there are only two ends where they can be placed. The book does not mention this possibility, and in fact it can only happen if one of the doubles in question is the [0-0]. However, it is hard to imagine that the holder of the [0-0] would want to waste it in this way, so probably the problem never arises.
  4. It is possible to think of many further combinations of rules that players might announce, for example 'triangle, then ordinary double cross', or 'volapük, first here then there', or 'ordinary, first here and then there, then matador cross'. However, the book only gives the 17 possibilities that are listed above, and the book says (p23, rule 5) that the player on set must 'kiezen uit de zeventien hierboven genoemde soorten' (choose from the 17 game types listed above), so it seems clear that these are the only games allowed. In practice they do cover all the variants that a player is likely to want to announce. However, it would be entirely possible to play a version of Nos in which additional rule combinations were permitted.